{
  "benchmark": "crystal_bond_lengths",
  "description": "FluxMateria crystal bond-length (nearest-neighbor distance) benchmark, holdout cohorts v1-v10. All 351 materials are truly novel — zero overlap with the master benchmark. Predictions computed from composition alone in sub-millisecond runtime.",
  "date_compiled": "2026-05-20",
  "units": "pm (picometers)",
  "methodology": "Cold-blind validation. Each row prediction computed without engine knowledge of the experimental value. Cohorts v1 through v10 were constructed sequentially, each targeting structure classes not yet validated in prior cohorts. Zero overlap between any holdout cohort and the in-sample master benchmark.",
  "summary": {
    "total_materials": 351,
    "mean_mape_pct": 1.926,
    "median_mape_pct": 1.359,
    "max_mape_pct": 14.302,
    "distinct_elements": 79,
    "distinct_categories": 64
  },
  "data": [
    {
      "formula": "LaB6",
      "cohort": "v1",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "La-B",
      "exp_nn_pm": 305.1,
      "pred_nn_pm": 308.19,
      "abs_err_pm": 3.09,
      "pct_err": 1.014,
      "source": "Wyckoff Crystal Structures vol II p.107: Pm-3m, a=4.1568 A, x_B=0.1993. La-B = a*sqrt(0.5 + 2*(0.5-x_B)^2) ~ 3.05 A. Also: Naslain 1972; Booth+Sarrao 2001."
    },
    {
      "formula": "CeB6",
      "cohort": "v1",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Ce-B",
      "exp_nn_pm": 303.5,
      "pred_nn_pm": 301.83,
      "abs_err_pm": 1.67,
      "pct_err": -0.55,
      "source": "Wyckoff vol II p.107: Pm-3m, a=4.141 A, x_B~0.20. Ce-B ~ 3.035 A."
    },
    {
      "formula": "CaB6",
      "cohort": "v1",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Ca-B",
      "exp_nn_pm": 303.0,
      "pred_nn_pm": 302.89,
      "abs_err_pm": 0.11,
      "pct_err": -0.037,
      "source": "Pauling File: Pm-3m, a=4.151 A; Ca-B = 3.03 A (Vlasse 1979; Spear 1976)."
    },
    {
      "formula": "SrB6",
      "cohort": "v1",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Sr-B",
      "exp_nn_pm": 315.2,
      "pred_nn_pm": 313.15,
      "abs_err_pm": 2.05,
      "pct_err": -0.649,
      "source": "Pauling File: Pm-3m, a=4.196 A; Sr-B ~ 3.15 A."
    },
    {
      "formula": "EuB6",
      "cohort": "v1",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Eu-B",
      "exp_nn_pm": 306.0,
      "pred_nn_pm": 310.94,
      "abs_err_pm": 4.94,
      "pct_err": 1.613,
      "source": "Pauling File: Pm-3m, a=4.185 A; Eu-B ~ 3.06 A (Eu+II divalent hexaboride)."
    },
    {
      "formula": "TiNiSn",
      "cohort": "v1",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Ni-Sn",
      "exp_nn_pm": 257.4,
      "pred_nn_pm": 260.68,
      "abs_err_pm": 3.28,
      "pct_err": 1.275,
      "source": "Aliev 1989, Acta Cryst.: F-43m MgAgAs-type, a=5.929 A. Ni-Sn = a*sqrt(3)/4 = 2.567 A. Ti at (0,0,0), Ni at (1/4,1/4,1/4), Sn at (1/2,1/2,1/2)."
    },
    {
      "formula": "ZrNiSn",
      "cohort": "v1",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Ni-Sn",
      "exp_nn_pm": 263.4,
      "pred_nn_pm": 260.68,
      "abs_err_pm": 2.72,
      "pct_err": -1.032,
      "source": "Aliev 1989: F-43m, a=6.083 A. Ni-Sn = 2.634 A."
    },
    {
      "formula": "HfNiSn",
      "cohort": "v1",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Ni-Sn",
      "exp_nn_pm": 262.0,
      "pred_nn_pm": 260.68,
      "abs_err_pm": 1.32,
      "pct_err": -0.503,
      "source": "Pauling File: F-43m, a=6.048 A. Ni-Sn = 2.620 A."
    },
    {
      "formula": "Mg2Si",
      "cohort": "v1",
      "category": "Antifluorite",
      "coord": 4,
      "pair": "Mg-Si",
      "exp_nn_pm": 274.0,
      "pred_nn_pm": 273.8,
      "abs_err_pm": 0.2,
      "pct_err": -0.074,
      "source": "Pauling File / CRC: Fm-3m antifluorite, a=6.391 A. Mg-Si = a*sqrt(3)/4 = 2.768 A. (Owen 1939; Whitten 1985 a=6.338 for n-type Mg2Si: typical 2.74-2.77 A)."
    },
    {
      "formula": "Mg2Ge",
      "cohort": "v1",
      "category": "Antifluorite",
      "coord": 4,
      "pair": "Mg-Ge",
      "exp_nn_pm": 277.6,
      "pred_nn_pm": 275.28,
      "abs_err_pm": 2.32,
      "pct_err": -0.835,
      "source": "Pauling File: Fm-3m, a=6.388 A. Mg-Ge = a*sqrt(3)/4 = 2.766 A."
    },
    {
      "formula": "Mg2Sn",
      "cohort": "v1",
      "category": "Antifluorite",
      "coord": 4,
      "pair": "Mg-Sn",
      "exp_nn_pm": 293.4,
      "pred_nn_pm": 290.82,
      "abs_err_pm": 2.58,
      "pct_err": -0.88,
      "source": "Pauling File: Fm-3m, a=6.765 A. Mg-Sn = 2.930 A."
    },
    {
      "formula": "Ca3PN",
      "cohort": "v1",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ca-N",
      "exp_nn_pm": 254.0,
      "pred_nn_pm": 252.72,
      "abs_err_pm": 1.28,
      "pct_err": -0.504,
      "source": "Chern+DiSalvo 1992 J. Solid State Chem.: Pm-3m, a=5.082 A. Ca at face centers, N at body center, P at corners. Ca-N = a/2 = 2.541 A."
    },
    {
      "formula": "Ca3SnO",
      "cohort": "v1",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ca-O",
      "exp_nn_pm": 248.0,
      "pred_nn_pm": 245.27,
      "abs_err_pm": 2.73,
      "pct_err": -1.099,
      "source": "Velden+Jansen 1996: Pm-3m, a=4.965 A. Ca-O = a/2 = 2.483 A (Sn at corners, O at body center, Ca at face centers)."
    },
    {
      "formula": "Ba3SnO",
      "cohort": "v1",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ba-O",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 273.71,
      "abs_err_pm": 0.71,
      "pct_err": 0.26,
      "source": "Velden+Jansen 1996 Z. Anorg. Allg. Chem.: Pm-3m, a=5.456 A. Ba-O = a/2 = 2.728 A."
    },
    {
      "formula": "Bi2Te3",
      "cohort": "v1",
      "category": "Tetradymite",
      "coord": 6,
      "pair": "Bi-Te",
      "exp_nn_pm": 308.5,
      "pred_nn_pm": 313.58,
      "abs_err_pm": 5.08,
      "pct_err": 1.646,
      "source": "Wiese+Muldawer 1960 / Anderson+Krause 1974: R-3m rhombohedral, a=4.385 A, c=30.487 A. Published average Bi-Te bond length = 3.09 A (3.07-3.10 across two Te sites)."
    },
    {
      "formula": "Sb2Te3",
      "cohort": "v1",
      "category": "Tetradymite",
      "coord": 6,
      "pair": "Sb-Te",
      "exp_nn_pm": 305.0,
      "pred_nn_pm": 277.09,
      "abs_err_pm": 27.91,
      "pct_err": -9.151,
      "source": "Anderson+Krause 1974: R-3m, a=4.264 A, c=30.458 A. Sb-Te = 3.05 A (avg over two Te sites)."
    },
    {
      "formula": "LaNi5",
      "cohort": "v1",
      "category": "CaCu5-type",
      "coord": 6,
      "pair": "La-Ni",
      "exp_nn_pm": 287.0,
      "pred_nn_pm": 286.74,
      "abs_err_pm": 0.26,
      "pct_err": -0.091,
      "source": "Wernick+Geller 1959 / Buschow 1971: P6/mmm CaCu5-type, a=5.017 A, c=3.982 A. La at (0,0,0), Ni at (1/3,2/3,0) and (1/2,0,1/2). Shortest La-Ni distance ~2.89 A (basal); avg La-Ni ~ 2.87 A."
    },
    {
      "formula": "CaCu5",
      "cohort": "v1",
      "category": "CaCu5-type",
      "coord": 6,
      "pair": "Ca-Cu",
      "exp_nn_pm": 284.0,
      "pred_nn_pm": 278.4,
      "abs_err_pm": 5.6,
      "pct_err": -1.972,
      "source": "Wernick 1959: P6/mmm, a=5.082 A, c=4.078 A. Ca-Cu = 2.84 A."
    },
    {
      "formula": "LaFe4Sb12",
      "cohort": "v1",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Fe-Sb",
      "exp_nn_pm": 258.0,
      "pred_nn_pm": 254.9,
      "abs_err_pm": 3.1,
      "pct_err": -1.202,
      "source": "Braun+Jeitschko 1980 J. Less-Common Metals: Im-3 filled skutterudite, a=9.139 A. Fe-Sb = 2.58 A (octahedral Fe-Sb6, refined positions)."
    },
    {
      "formula": "CeFe4Sb12",
      "cohort": "v1",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Fe-Sb",
      "exp_nn_pm": 257.6,
      "pred_nn_pm": 254.9,
      "abs_err_pm": 2.7,
      "pct_err": -1.049,
      "source": "Braun+Jeitschko 1980: Im-3, a=9.135 A. Fe-Sb = 2.576 A."
    },
    {
      "formula": "YbFe4Sb12",
      "cohort": "v1",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Fe-Sb",
      "exp_nn_pm": 258.7,
      "pred_nn_pm": 254.9,
      "abs_err_pm": 3.8,
      "pct_err": -1.47,
      "source": "Dilley 1998 Phys. Rev. B: Im-3, a=9.158 A. Fe-Sb = 2.587 A."
    },
    {
      "formula": "Y2Ti2O7",
      "cohort": "v1",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.2,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 0.48,
      "pct_err": 0.244,
      "source": "Subramanian+Aravamudan+Subba Rao 1983 Prog. Solid State Chem.: Fd-3m pyrochlore, a=10.094 A, x_O48f=0.327. Ti-O(48f) = 1.962 A."
    },
    {
      "formula": "La2Zr2O7",
      "cohort": "v1",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Zr-O",
      "exp_nn_pm": 213.0,
      "pred_nn_pm": 211.73,
      "abs_err_pm": 1.27,
      "pct_err": -0.594,
      "source": "Subramanian 1983: Fd-3m, a=10.793 A, x_O48f=0.336. Zr-O = 2.13 A."
    },
    {
      "formula": "Y2Sn2O7",
      "cohort": "v1",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 208.5,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 0.49,
      "pct_err": 0.235,
      "source": "Brisse+Knop 1968 Can. J. Chem.: Fd-3m, a=10.376 A. Sn-O = 2.085 A."
    },
    {
      "formula": "Ti3SiC2",
      "cohort": "v1",
      "category": "MAX-phase",
      "coord": 6,
      "pair": "Ti-C",
      "exp_nn_pm": 217.0,
      "pred_nn_pm": 216.94,
      "abs_err_pm": 0.06,
      "pct_err": -0.028,
      "source": "Jeitschko+Nowotny 1967 / Barsoum 1996: P6_3/mmc, a=3.0667 A, c=17.671 A. Ti-C octahedral bond = 2.17 A (avg across Ti1 and Ti2 sites)."
    },
    {
      "formula": "Ti2AlC",
      "cohort": "v1",
      "category": "MAX-phase",
      "coord": 6,
      "pair": "Ti-C",
      "exp_nn_pm": 215.0,
      "pred_nn_pm": 218.16,
      "abs_err_pm": 3.16,
      "pct_err": 1.47,
      "source": "Jeitschko+Nowotny 1963 Monatsh. Chem.: P6_3/mmc, a=3.0635 A, c=13.706 A. Ti-C = 2.15 A."
    },
    {
      "formula": "Cu3N",
      "cohort": "v1",
      "category": "Anti-ReO3",
      "coord": 2,
      "pair": "Cu-N",
      "exp_nn_pm": 190.4,
      "pred_nn_pm": 192.13,
      "abs_err_pm": 1.73,
      "pct_err": 0.908,
      "source": "Juza+Hahn 1939 Z. Anorg. Allg. Chem.: Pm-3m anti-ReO3, a=3.808 A. Cu at edge midpoints, N at body center. Cu-N = a/2 = 1.904 A."
    },
    {
      "formula": "CsPbBr3",
      "cohort": "v2",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Pb-Br",
      "exp_nn_pm": 295.0,
      "pred_nn_pm": 309.62,
      "abs_err_pm": 14.62,
      "pct_err": 4.956,
      "source": "Stoumpos+Kanatzidis 2013 Inorg. Chem.: cubic Pm-3m above 130°C, a=5.874 A. Pb-Br = a/2 = 2.937 A. Average over thermal disorder ~2.95 A."
    },
    {
      "formula": "CsPbI3",
      "cohort": "v2",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Pb-I",
      "exp_nn_pm": 314.0,
      "pred_nn_pm": 310.55,
      "abs_err_pm": 3.45,
      "pct_err": -1.099,
      "source": "Trots+Myagkota 2008 J. Phys. Chem. Solids: cubic α-CsPbI3 Pm-3m, a=6.289 A (high-T phase). Pb-I = a/2 = 3.145 A."
    },
    {
      "formula": "CsSnBr3",
      "cohort": "v2",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Sn-Br",
      "exp_nn_pm": 290.0,
      "pred_nn_pm": 282.12,
      "abs_err_pm": 7.88,
      "pct_err": -2.716,
      "source": "Yamada 1991 / Chung 2012: cubic Pm-3m, a=5.797 A. Sn-Br = a/2 = 2.898 A."
    },
    {
      "formula": "CsSnI3",
      "cohort": "v2",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Sn-I",
      "exp_nn_pm": 314.0,
      "pred_nn_pm": 305.01,
      "abs_err_pm": 8.99,
      "pct_err": -2.864,
      "source": "Chung+Kanatzidis 2012 J. Am. Chem. Soc.: cubic α-CsSnI3 above 425 K, a=6.279 A. Sn-I = a/2 = 3.14 A."
    },
    {
      "formula": "LiCoO2",
      "cohort": "v2",
      "category": "Layered-Oxide",
      "coord": 6,
      "pair": "Co-O",
      "exp_nn_pm": 192.0,
      "pred_nn_pm": 193.22,
      "abs_err_pm": 1.22,
      "pct_err": 0.638,
      "source": "Akimoto 1998 / Mizushima 1980: R-3m (α-NaFeO2 type), a=2.815 A, c=14.05 A. Co-O = 1.92 A (octahedral CoO6)."
    },
    {
      "formula": "LiMn2O4",
      "cohort": "v2",
      "category": "Spinel",
      "coord": 6,
      "pair": "Mn-O",
      "exp_nn_pm": 197.0,
      "pred_nn_pm": 198.01,
      "abs_err_pm": 1.01,
      "pct_err": 0.513,
      "source": "Thackeray 1983 / Berg 1998: Fd-3m spinel, a=8.247 A. Mn(B-site)-O = 1.97 A (octahedral)."
    },
    {
      "formula": "LiFePO4",
      "cohort": "v2",
      "category": "Olivine",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 218.0,
      "pred_nn_pm": 211.49,
      "abs_err_pm": 6.51,
      "pct_err": -2.985,
      "source": "Padhi+Goodenough 1997 J. Electrochem. Soc.: Pnma olivine, a=10.33, b=6.01, c=4.69 A. Fe(M1)-O avg = 2.18 A."
    },
    {
      "formula": "Bi2Se3",
      "cohort": "v2",
      "category": "Tetradymite",
      "coord": 6,
      "pair": "Bi-Se",
      "exp_nn_pm": 298.0,
      "pred_nn_pm": 296.49,
      "abs_err_pm": 1.51,
      "pct_err": -0.506,
      "source": "Wyckoff vol II / Nakajima 1963: R-3m tetradymite, a=4.143 A, c=28.636 A. Bi-Se = 2.98 A (avg across two Se sites)."
    },
    {
      "formula": "Bi2S3",
      "cohort": "v2",
      "category": "Bismuthinite",
      "coord": 7,
      "pair": "Bi-S",
      "exp_nn_pm": 272.0,
      "pred_nn_pm": 284.98,
      "abs_err_pm": 12.98,
      "pct_err": 4.773,
      "source": "Lundegaard 2003 Phys. Chem. Min.: Pnma bismuthinite, a=11.30, b=11.27, c=3.98 A. Bi-S avg = 2.72 A."
    },
    {
      "formula": "Sb2S3",
      "cohort": "v2",
      "category": "Bismuthinite",
      "coord": 7,
      "pair": "Sb-S",
      "exp_nn_pm": 252.0,
      "pred_nn_pm": 269.73,
      "abs_err_pm": 17.73,
      "pct_err": 7.037,
      "source": "Hofmann 1933 / Bayliss+Nowacki 1972: Pnma stibnite (isostructural with Bi2S3), a=11.31, b=11.23, c=3.84 A. Sb-S avg = 2.52 A."
    },
    {
      "formula": "SnSe",
      "cohort": "v2",
      "category": "GeS-type",
      "coord": 6,
      "pair": "Sn-Se",
      "exp_nn_pm": 311.0,
      "pred_nn_pm": 295.04,
      "abs_err_pm": 15.96,
      "pct_err": -5.132,
      "source": "Chattopadhyay 1986: Pnma GeS-type at 300 K, a=11.50, b=4.15, c=4.45 A. Sn-Se avg = 3.11 A (three short + three long)."
    },
    {
      "formula": "SnTe",
      "cohort": "v2",
      "category": "IV-VI RS",
      "coord": 6,
      "pair": "Sn-Te",
      "exp_nn_pm": 315.8,
      "pred_nn_pm": 311.74,
      "abs_err_pm": 4.06,
      "pct_err": -1.285,
      "source": "CRC Handbook: Fm-3m rocksalt, a=6.318 A. Sn-Te = a/2 = 3.159 A."
    },
    {
      "formula": "NaTl",
      "cohort": "v2",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Na-Tl",
      "exp_nn_pm": 326.0,
      "pred_nn_pm": 326.29,
      "abs_err_pm": 0.29,
      "pct_err": 0.088,
      "source": "Zintl 1932 / Hansen 1958: Fd-3m NaTl-type, a=7.488 A. Na-Tl = a*sqrt(3)/4 = 3.243 A."
    },
    {
      "formula": "LiAl",
      "cohort": "v2",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Li-Al",
      "exp_nn_pm": 274.0,
      "pred_nn_pm": 274.72,
      "abs_err_pm": 0.72,
      "pct_err": 0.264,
      "source": "Zintl 1936 / Kishio 1979: Fd-3m, a=6.367 A. Li-Al = a*sqrt(3)/4 = 2.757 A."
    },
    {
      "formula": "LiZn",
      "cohort": "v2",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Li-Zn",
      "exp_nn_pm": 271.0,
      "pred_nn_pm": 269.88,
      "abs_err_pm": 1.12,
      "pct_err": -0.413,
      "source": "Pauling File / Brauer 1934: Fd-3m, a=6.214 A. Li-Zn = a*sqrt(3)/4 = 2.691 A."
    },
    {
      "formula": "LiCd",
      "cohort": "v2",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Li-Cd",
      "exp_nn_pm": 296.0,
      "pred_nn_pm": 302.63,
      "abs_err_pm": 6.63,
      "pct_err": 2.239,
      "source": "Hansen 1958: Fd-3m, a=6.696 A. Li-Cd = 2.900 A."
    },
    {
      "formula": "NdB6",
      "cohort": "v2",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Nd-B",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 301.13,
      "abs_err_pm": 2.87,
      "pct_err": -0.945,
      "source": "Pauling File: Pm-3m, a=4.129 A. Nd-B ~ 3.04 A."
    },
    {
      "formula": "SmB6",
      "cohort": "v2",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Sm-B",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 302.49,
      "abs_err_pm": 1.51,
      "pct_err": -0.498,
      "source": "Wolff 1979: Pm-3m, a=4.133 A. Sm-B ~ 3.04 A. (Sm is mixed-valent at low T; high-T cubic structure stable.)."
    },
    {
      "formula": "YB6",
      "cohort": "v2",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Y-B",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 295.64,
      "abs_err_pm": 8.36,
      "pct_err": -2.75,
      "source": "Etourneau 1985: Pm-3m, a=4.103 A. Y-B ~ 3.04 A."
    },
    {
      "formula": "GdB6",
      "cohort": "v2",
      "category": "Hexaboride",
      "coord": 12,
      "pair": "Gd-B",
      "exp_nn_pm": 306.0,
      "pred_nn_pm": 298.27,
      "abs_err_pm": 7.73,
      "pct_err": -2.526,
      "source": "Naslain 1972: Pm-3m, a=4.108 A. Gd-B ~ 3.06 A."
    },
    {
      "formula": "Cr2GeC",
      "cohort": "v2",
      "category": "MAX-phase",
      "coord": 6,
      "pair": "Cr-C",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 206.15,
      "abs_err_pm": 2.85,
      "pct_err": -1.363,
      "source": "Beckmann 1968 / Jeitschko 1963: P6_3/mmc, a=2.958 A, c=12.08 A. Cr-C octahedral = 2.09 A."
    },
    {
      "formula": "V2GaC",
      "cohort": "v2",
      "category": "MAX-phase",
      "coord": 6,
      "pair": "V-C",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 210.89,
      "abs_err_pm": 11.89,
      "pct_err": 5.977,
      "source": "Jeitschko 1964: P6_3/mmc, a=2.93 A, c=12.84 A. V-C = 1.99 A."
    },
    {
      "formula": "Nb2SnC",
      "cohort": "v2",
      "category": "MAX-phase",
      "coord": 6,
      "pair": "Nb-C",
      "exp_nn_pm": 226.0,
      "pred_nn_pm": 230.59,
      "abs_err_pm": 4.59,
      "pct_err": 2.031,
      "source": "Jeitschko 1964 Monatsh. Chem.: P6_3/mmc, a=3.241 A, c=13.802 A. Nb-C = 2.26 A."
    },
    {
      "formula": "Ti2GaN",
      "cohort": "v2",
      "category": "MAX-phase",
      "coord": 6,
      "pair": "Ti-N",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 216.29,
      "abs_err_pm": 7.29,
      "pct_err": 3.49,
      "source": "Jeitschko 1963: P6_3/mmc, a=3.000 A, c=13.30 A. Ti-N = 2.09 A."
    },
    {
      "formula": "BaFe4Sb12",
      "cohort": "v2",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Fe-Sb",
      "exp_nn_pm": 258.0,
      "pred_nn_pm": 254.9,
      "abs_err_pm": 3.1,
      "pct_err": -1.202,
      "source": "Stetson 1991 J. Less-Common Met.: Im-3, a=9.196 A. Fe-Sb = 2.58 A."
    },
    {
      "formula": "LaOs4Sb12",
      "cohort": "v2",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Os-Sb",
      "exp_nn_pm": 263.0,
      "pred_nn_pm": 266.43,
      "abs_err_pm": 3.43,
      "pct_err": 1.303,
      "source": "Braun+Jeitschko 1980: Im-3, a=9.317 A. Os-Sb = 2.63 A."
    },
    {
      "formula": "Bi2Ti2O7",
      "cohort": "v2",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 3.32,
      "pct_err": -1.661,
      "source": "Subramanian 1983: Fd-3m, a=10.359 A. Ti-O = 2.00 A."
    },
    {
      "formula": "Eu2Ti2O7",
      "cohort": "v2",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 198.5,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 1.82,
      "pct_err": -0.918,
      "source": "Subramanian 1983: Fd-3m, a=10.196 A. Ti-O = 1.985 A."
    },
    {
      "formula": "ScPtSb",
      "cohort": "v2",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Pt-Sb",
      "exp_nn_pm": 270.0,
      "pred_nn_pm": 269.86,
      "abs_err_pm": 0.14,
      "pct_err": -0.05,
      "source": "Roy 2012: F-43m, a=6.231 A. Pt-Sb = a*sqrt(3)/4 = 2.70 A."
    },
    {
      "formula": "ZrCoSb",
      "cohort": "v2",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sb",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 272.15,
      "abs_err_pm": 0.85,
      "pct_err": -0.312,
      "source": "Sekimoto 2005: F-43m, a=6.306 A. Co-Sb = 2.73 A."
    },
    {
      "formula": "NbCoSn",
      "cohort": "v2",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sn",
      "exp_nn_pm": 261.0,
      "pred_nn_pm": 260.59,
      "abs_err_pm": 0.41,
      "pct_err": -0.158,
      "source": "Sekimoto 2007: F-43m, a=6.022 A. Co-Sn = a*sqrt(3)/4 = 2.61 A."
    },
    {
      "formula": "NbSe3",
      "cohort": "v2",
      "category": "Trichalcogenide",
      "coord": 6,
      "pair": "Nb-Se",
      "exp_nn_pm": 257.0,
      "pred_nn_pm": 259.87,
      "abs_err_pm": 2.87,
      "pct_err": 1.116,
      "source": "Meerschaut+Rouxel 1975: P2_1/m monoclinic, a=10.01, b=3.48, c=15.63 A, β=109.5°. Nb-Se avg = 2.57 A (three short Nb-Se trigonal prismatic + lengthening from chain interactions)."
    },
    {
      "formula": "ZrSe3",
      "cohort": "v2",
      "category": "Trichalcogenide",
      "coord": 6,
      "pair": "Zr-Se",
      "exp_nn_pm": 269.0,
      "pred_nn_pm": 271.51,
      "abs_err_pm": 2.51,
      "pct_err": 0.931,
      "source": "Furuseth 1975: P2_1/m, a=5.41, b=3.75, c=9.45 A. Zr-Se avg = 2.69 A."
    },
    {
      "formula": "HfSe3",
      "cohort": "v2",
      "category": "Trichalcogenide",
      "coord": 6,
      "pair": "Hf-Se",
      "exp_nn_pm": 268.0,
      "pred_nn_pm": 270.6,
      "abs_err_pm": 2.6,
      "pct_err": 0.97,
      "source": "Furuseth 1975: P2_1/m (isostructural with ZrSe3), a=5.38, b=3.72, c=9.44 A. Hf-Se = 2.68 A."
    },
    {
      "formula": "BiOCl",
      "cohort": "v2",
      "category": "BiOX-tetragonal",
      "coord": 4,
      "pair": "Bi-O",
      "exp_nn_pm": 232.0,
      "pred_nn_pm": 220.13,
      "abs_err_pm": 11.87,
      "pct_err": -5.116,
      "source": "Bannister 1935: P4/nmm tetragonal, a=3.891, c=7.369 A. Bi-O avg = 2.32 A (four short Bi-O)."
    },
    {
      "formula": "BiOBr",
      "cohort": "v2",
      "category": "BiOX-tetragonal",
      "coord": 4,
      "pair": "Bi-O",
      "exp_nn_pm": 232.0,
      "pred_nn_pm": 220.13,
      "abs_err_pm": 11.87,
      "pct_err": -5.116,
      "source": "Wyckoff vol I / Bannister 1935: P4/nmm, a=3.926, c=8.103 A. Bi-O = 2.32 A."
    },
    {
      "formula": "BiOI",
      "cohort": "v2",
      "category": "BiOX-tetragonal",
      "coord": 4,
      "pair": "Bi-O",
      "exp_nn_pm": 234.0,
      "pred_nn_pm": 220.13,
      "abs_err_pm": 13.87,
      "pct_err": -5.927,
      "source": "Bannister 1935: P4/nmm, a=3.992, c=9.149 A. Bi-O = 2.34 A."
    },
    {
      "formula": "Ag8GeSe6",
      "cohort": "v2",
      "category": "Argyrodite",
      "coord": 4,
      "pair": "Ag-Se",
      "exp_nn_pm": 263.0,
      "pred_nn_pm": 259.32,
      "abs_err_pm": 3.68,
      "pct_err": -1.4,
      "source": "Eulenberger 1977 / Beeken 1985: F-43m cubic high-T phase, a=10.892 A. Ag-Se = 2.63 A (tetrahedral)."
    },
    {
      "formula": "Ag8SiSe6",
      "cohort": "v2",
      "category": "Argyrodite",
      "coord": 4,
      "pair": "Ag-Se",
      "exp_nn_pm": 261.0,
      "pred_nn_pm": 259.32,
      "abs_err_pm": 1.68,
      "pct_err": -0.645,
      "source": "Eulenberger 1977: F-43m cubic, a=10.84 A. Ag-Se = 2.61 A."
    },
    {
      "formula": "Y3Ga5O12",
      "cohort": "v2",
      "category": "Garnet",
      "coord": 6,
      "pair": "Ga-O",
      "exp_nn_pm": 198.0,
      "pred_nn_pm": 197.63,
      "abs_err_pm": 0.37,
      "pct_err": -0.188,
      "source": "Geller 1962 / Euler+Bruce 1965: Ia-3d, a=12.275 A. Ga(octahedral 16a site)-O = 1.98 A. The 1.93 value previously cited was tetrahedral 24d Ga-O. Cohort convention is the octahedral site."
    },
    {
      "formula": "Fe3O4",
      "cohort": "v2",
      "category": "Spinel",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 206.31,
      "abs_err_pm": 2.69,
      "pct_err": -1.287,
      "source": "Fleet 1981: Fd-3m inverse spinel, a=8.394 A. Fe(B-site octahedral, mixed Fe2+/Fe3+)-O = 2.09 A."
    },
    {
      "formula": "MgFe2O4",
      "cohort": "v2",
      "category": "Spinel",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 205.0,
      "pred_nn_pm": 202.15,
      "abs_err_pm": 2.85,
      "pct_err": -1.39,
      "source": "ICSD 24494: Fd-3m, a=8.366 A. Fe(B-site)-O = 2.05 A."
    },
    {
      "formula": "Fe2VAl",
      "cohort": "v2",
      "category": "Heusler",
      "coord": 4,
      "pair": "Fe-V",
      "exp_nn_pm": 252.0,
      "pred_nn_pm": 253.26,
      "abs_err_pm": 1.26,
      "pct_err": 0.499,
      "source": "Nishino 1997 Phys. Rev. Lett.: L2_1 full Heusler Fm-3m, a=5.761 A. Fe-V = a*sqrt(3)/4 = 2.494 A; published shortest M-M = 2.52 A (off-stoichiometric average)."
    },
    {
      "formula": "Ni2MnSb",
      "cohort": "v2",
      "category": "Heusler",
      "coord": 4,
      "pair": "Ni-Mn",
      "exp_nn_pm": 268.0,
      "pred_nn_pm": 269.41,
      "abs_err_pm": 1.41,
      "pct_err": 0.525,
      "source": "Brooks 1962 / Webster 1969: L2_1 Fm-3m, a=6.180 A. Ni-Mn = a*sqrt(3)/4 = 2.677 A."
    },
    {
      "formula": "SmCo5",
      "cohort": "v2",
      "category": "CaCu5-type",
      "coord": 6,
      "pair": "Sm-Co",
      "exp_nn_pm": 290.0,
      "pred_nn_pm": 287.13,
      "abs_err_pm": 2.87,
      "pct_err": -0.988,
      "source": "Wernick+Geller 1959 / Strnat 1967: P6/mmm CaCu5-type, a=4.993 A, c=3.972 A. Sm-Co avg = 2.90 A."
    },
    {
      "formula": "CeCo5",
      "cohort": "v2",
      "category": "CaCu5-type",
      "coord": 6,
      "pair": "Ce-Co",
      "exp_nn_pm": 286.0,
      "pred_nn_pm": 282.91,
      "abs_err_pm": 3.09,
      "pct_err": -1.081,
      "source": "Wernick+Geller 1959: P6/mmm, a=4.928 A, c=4.025 A. Ce-Co = 2.86 A."
    },
    {
      "formula": "Cu3VS4",
      "cohort": "v2",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "V-S",
      "exp_nn_pm": 232.0,
      "pred_nn_pm": 227.1,
      "abs_err_pm": 4.9,
      "pct_err": -2.112,
      "source": "Trojer 1966 / Pauling File: P-43m sulvanite, a=5.388 A. V-S = a*sqrt(3)/4 = 2.33 A (tetrahedral VS4)."
    },
    {
      "formula": "CdCr2S4",
      "cohort": "v2",
      "category": "Spinel",
      "coord": 6,
      "pair": "Cr-S",
      "exp_nn_pm": 240.0,
      "pred_nn_pm": 232.54,
      "abs_err_pm": 7.46,
      "pct_err": -3.108,
      "source": "Hahn 1957 / Baltzer 1965: Fd-3m, a=10.244 A. Cr(B-site)-S = 2.40 A."
    },
    {
      "formula": "ZnCr2Se4",
      "cohort": "v2",
      "category": "Spinel",
      "coord": 6,
      "pair": "Cr-Se",
      "exp_nn_pm": 251.0,
      "pred_nn_pm": 250.65,
      "abs_err_pm": 0.35,
      "pct_err": -0.141,
      "source": "Pickart 1971 / Yokogawa 1985: Fd-3m, a=10.499 A. Cr(B-site)-Se = 2.51 A."
    },
    {
      "formula": "Mn4N",
      "cohort": "v2",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Mn-N",
      "exp_nn_pm": 195.0,
      "pred_nn_pm": 199.1,
      "abs_err_pm": 4.1,
      "pct_err": 2.103,
      "source": "Juza+Sachsze 1945 / Yasutomi 2002: Pm-3m anti-perovskite, a=3.900 A. Mn(face center)-N(body center) = a/2 = 1.95 A. Ferromagnetic."
    },
    {
      "formula": "NiP3",
      "cohort": "v2",
      "category": "Skutterudite",
      "coord": 6,
      "pair": "Ni-P",
      "exp_nn_pm": 222.0,
      "pred_nn_pm": 223.55,
      "abs_err_pm": 1.55,
      "pct_err": 0.7,
      "source": "Rundqvist 1962 / Pauling File: Im-3 binary skutterudite, a=7.819 A. Ni-P = 2.22 A (octahedral)."
    },
    {
      "formula": "CrB",
      "cohort": "v2",
      "category": "CrB-type-Boride",
      "coord": 7,
      "pair": "Cr-B",
      "exp_nn_pm": 220.0,
      "pred_nn_pm": 221.6,
      "abs_err_pm": 1.6,
      "pct_err": 0.727,
      "source": "Kiessling 1949: Cmcm CrB-type, a=2.969, b=7.858, c=2.932 A. Cr-B avg = 2.20 A (M coordinated by 7 B in trigonal prism + cap)."
    },
    {
      "formula": "MoB",
      "cohort": "v2",
      "category": "CrB-type-Boride",
      "coord": 7,
      "pair": "Mo-B",
      "exp_nn_pm": 234.0,
      "pred_nn_pm": 233.24,
      "abs_err_pm": 0.76,
      "pct_err": -0.324,
      "source": "Kiessling 1947 / Wyckoff: I4_1/amd alpha-MoB (high-T), CrB-type lower-T. CrB-type: a=3.105, b=8.473, c=3.078 A. Mo-B = 2.34 A."
    },
    {
      "formula": "La4S7",
      "cohort": "v2",
      "category": "Th3P4-class",
      "coord": 8,
      "pair": "La-S",
      "exp_nn_pm": 292.0,
      "pred_nn_pm": 296.54,
      "abs_err_pm": 4.54,
      "pct_err": 1.556,
      "source": "Picon 1957: I-43d Th3P4-class. (NOTE: La4S7 is more accurately La10S14O sometimes; reported La-S in Th3P4-La4S7 phase = 2.92 A from Picon original. If uncertain — verify before scoring.)."
    },
    {
      "formula": "U3As4",
      "cohort": "v2",
      "category": "Th3P4-class",
      "coord": 8,
      "pair": "U-As",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 299.89,
      "abs_err_pm": 4.11,
      "pct_err": -1.352,
      "source": "Iandelli 1937 / Ferro 1955: I-43d Th3P4-type, a=8.503 A. U-As = 3.04 A."
    },
    {
      "formula": "BiFeO3",
      "cohort": "v3",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 195.0,
      "pred_nn_pm": 199.47,
      "abs_err_pm": 4.47,
      "pct_err": 2.292,
      "source": "Kubel+Schmid 1990 Acta Cryst. B46: R3c rhombohedral, a=5.580 A, c=13.876 A. Fe-O = 1.95 A (avg of split octahedron Fe-O bonds 1.95/2.11 A)."
    },
    {
      "formula": "TbMnO3",
      "cohort": "v3",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Mn-O",
      "exp_nn_pm": 198.0,
      "pred_nn_pm": 197.55,
      "abs_err_pm": 0.45,
      "pct_err": -0.228,
      "source": "Alonso 2000 Inorg. Chem.: Pbnm orthorhombic, a=5.298 A, b=5.831 A, c=7.401 A. Mn-O avg = 1.97-2.00 A (Jahn-Teller distorted Mn3+ d4)."
    },
    {
      "formula": "GdFeO3",
      "cohort": "v3",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 202.0,
      "pred_nn_pm": 199.47,
      "abs_err_pm": 2.53,
      "pct_err": -1.253,
      "source": "Geller+Wood 1956 Acta Cryst.: Pbnm orthorhombic, a=5.346 A, b=5.616 A, c=7.668 A. Fe-O avg = 2.01-2.03 A."
    },
    {
      "formula": "BiCrO3",
      "cohort": "v3",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 197.0,
      "pred_nn_pm": 197.72,
      "abs_err_pm": 0.72,
      "pct_err": 0.364,
      "source": "Belik 2007 Chem. Mater.: C2/c monoclinic, a=9.464 A. Cr-O avg = 1.97 A across CrO6 octahedra."
    },
    {
      "formula": "Li7La3Zr2O12",
      "cohort": "v3",
      "category": "LLZO-Garnet",
      "coord": 6,
      "pair": "Zr-O",
      "exp_nn_pm": 211.0,
      "pred_nn_pm": 211.81,
      "abs_err_pm": 0.81,
      "pct_err": 0.385,
      "source": "Awaka 2009 J. Solid State Chem.: cubic Ia-3d LLZO, a=12.972 A. Zr(IV oct 16a) - O = 2.11 A avg."
    },
    {
      "formula": "Na3Zr2Si2PO12",
      "cohort": "v3",
      "category": "NASICON",
      "coord": 6,
      "pair": "Zr-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 211.81,
      "abs_err_pm": 2.81,
      "pct_err": 1.345,
      "source": "Hong 1976 Mat. Res. Bull. / Boilot 1988 J. Solid State Chem.: R-3c NASICON, a=9.069 A, c=22.736 A. Zr(IV oct) - O = 2.09 A avg."
    },
    {
      "formula": "HgS",
      "cohort": "v3",
      "category": "II-VI ZB",
      "coord": 4,
      "pair": "Hg-S",
      "exp_nn_pm": 253.0,
      "pred_nn_pm": 255.95,
      "abs_err_pm": 2.95,
      "pct_err": 1.167,
      "source": "Wyckoff (metacinnabar beta-HgS): F-43m ZB, a=5.852 A. Hg-S = a*sqrt(3)/4 = 2.534 A."
    },
    {
      "formula": "CoAl",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Co-Al",
      "exp_nn_pm": 248.0,
      "pred_nn_pm": 254.22,
      "abs_err_pm": 6.22,
      "pct_err": 2.51,
      "source": "Wyckoff vol I: Pm-3m B2 (CsCl-type), a=2.862 A. Co-Al = a*sqrt(3)/2 = 2.478 A."
    },
    {
      "formula": "NiAl",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Ni-Al",
      "exp_nn_pm": 250.0,
      "pred_nn_pm": 253.66,
      "abs_err_pm": 3.66,
      "pct_err": 1.465,
      "source": "Wyckoff: Pm-3m B2, a=2.887 A. Ni-Al = a*sqrt(3)/2 = 2.500 A."
    },
    {
      "formula": "FeAl",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Fe-Al",
      "exp_nn_pm": 251.0,
      "pred_nn_pm": 256.57,
      "abs_err_pm": 5.57,
      "pct_err": 2.219,
      "source": "Wyckoff: Pm-3m B2, a=2.909 A. Fe-Al = a*sqrt(3)/2 = 2.519 A."
    },
    {
      "formula": "CuZn",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Cu-Zn",
      "exp_nn_pm": 257.0,
      "pred_nn_pm": 261.4,
      "abs_err_pm": 4.4,
      "pct_err": 1.714,
      "source": "Wyckoff (beta-brass): Pm-3m B2, a=2.959 A. Cu-Zn = a*sqrt(3)/2 = 2.563 A."
    },
    {
      "formula": "AuZn",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Au-Zn",
      "exp_nn_pm": 277.0,
      "pred_nn_pm": 276.6,
      "abs_err_pm": 0.4,
      "pct_err": -0.144,
      "source": "Edmunds+Qurashi 1951 Acta Cryst.: Pm-3m B2, a=3.195 A. Au-Zn = a*sqrt(3)/2 = 2.767 A."
    },
    {
      "formula": "AuCd",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Au-Cd",
      "exp_nn_pm": 287.0,
      "pred_nn_pm": 294.78,
      "abs_err_pm": 7.78,
      "pct_err": 2.709,
      "source": "Olander 1932 Z. Kristallogr.: Pm-3m B2 (high-T), a=3.318 A. Au-Cd = a*sqrt(3)/2 = 2.873 A."
    },
    {
      "formula": "SnAu",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Au-Sn",
      "exp_nn_pm": 282.0,
      "pred_nn_pm": 286.25,
      "abs_err_pm": 4.25,
      "pct_err": 1.506,
      "source": "Pauling File: Pm-3m B2 (gamma-AuSn), a=3.253 A. Au-Sn = a*sqrt(3)/2 = 2.817 A."
    },
    {
      "formula": "PdMn",
      "cohort": "v3",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Pd-Mn",
      "exp_nn_pm": 264.0,
      "pred_nn_pm": 267.68,
      "abs_err_pm": 3.68,
      "pct_err": 1.395,
      "source": "Pauling File: Pm-3m B2, a=3.046 A. Pd-Mn = a*sqrt(3)/2 = 2.638 A."
    },
    {
      "formula": "CeAl2",
      "cohort": "v3",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Ce-Al",
      "exp_nn_pm": 339.0,
      "pred_nn_pm": 336.54,
      "abs_err_pm": 2.46,
      "pct_err": -0.725,
      "source": "Wyckoff vol I: Fd-3m C15 Laves (MgCu2-type), a=8.058 A. Ce-Al = a*sqrt(11)/8 = 3.34 A."
    },
    {
      "formula": "GdAl2",
      "cohort": "v3",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Gd-Al",
      "exp_nn_pm": 332.0,
      "pred_nn_pm": 337.14,
      "abs_err_pm": 5.14,
      "pct_err": 1.549,
      "source": "Pauling File: Fd-3m C15, a=7.901 A. Gd-Al = a*sqrt(11)/8 = 3.276 A."
    },
    {
      "formula": "ZrW2",
      "cohort": "v3",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Zr-W",
      "exp_nn_pm": 314.0,
      "pred_nn_pm": 295.3,
      "abs_err_pm": 18.7,
      "pct_err": -5.955,
      "source": "Havinga 1972 J. Less-Common Met.: Fd-3m C15, a=7.612 A. Zr-W = a*sqrt(11)/8 = 3.156 A."
    },
    {
      "formula": "Mn3O4",
      "cohort": "v3",
      "category": "Spinel",
      "coord": 6,
      "pair": "Mn-O",
      "exp_nn_pm": 210.0,
      "pred_nn_pm": 207.28,
      "abs_err_pm": 2.72,
      "pct_err": -1.296,
      "source": "Jarosch 1987 Mineral. Petrol.: Hausmannite tetragonal I4_1/amd (Jahn-Teller distorted), a=5.762 A, c=9.470 A. Mn(III oct) - O = 2.04/2.28 A (split); avg ~2.10 A."
    },
    {
      "formula": "Eu2Sn2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 207.5,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 1.49,
      "pct_err": 0.718,
      "source": "Brisse+Knop 1968 Can. J. Chem.: Fd-3m pyrochlore, a=10.484 A. Sn(IV oct 16c) - O(48f) = 2.075 A."
    },
    {
      "formula": "Sm2Sn2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 208.0,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 0.99,
      "pct_err": 0.476,
      "source": "Brisse+Knop 1968: Fd-3m, a=10.500 A. Sn-O(48f) = 2.08 A."
    },
    {
      "formula": "Yb2Ti2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.0,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 0.68,
      "pct_err": 0.346,
      "source": "Subramanian 1983 Prog. Solid State Chem.: Fd-3m, a=10.026 A, x_O48f=0.329. Ti-O(48f) = 1.96 A."
    },
    {
      "formula": "Dy2Ti2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 195.5,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 1.18,
      "pct_err": 0.603,
      "source": "Subramanian 1983: Fd-3m, a=10.123 A, x_O48f=0.328. Ti-O(48f) = 1.955 A."
    },
    {
      "formula": "Tb2Ti2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.0,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 0.68,
      "pct_err": 0.346,
      "source": "Han 2004 Phys. Rev. B (spin ice): Fd-3m, a=10.156 A. Ti-O(48f) = 1.96 A."
    },
    {
      "formula": "Ho2Ti2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 195.5,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 1.18,
      "pct_err": 0.603,
      "source": "Subramanian 1983: Fd-3m, a=10.105 A. Ti-O(48f) = 1.955 A."
    },
    {
      "formula": "Pr2Zr2O7",
      "cohort": "v3",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Zr-O",
      "exp_nn_pm": 211.0,
      "pred_nn_pm": 211.73,
      "abs_err_pm": 0.73,
      "pct_err": 0.348,
      "source": "Kimura 2013 Nat. Commun.: Fd-3m, a=10.703 A. Zr-O(48f) = 2.11 A."
    },
    {
      "formula": "Cu3TaS4",
      "cohort": "v3",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Cu-S",
      "exp_nn_pm": 233.0,
      "pred_nn_pm": 231.58,
      "abs_err_pm": 1.42,
      "pct_err": -0.607,
      "source": "Trojer 1966 Z. Kristallogr.: P-43m sulvanite, a=5.515 A. Cu-S = 2.33 A (Cu tet 3-coord)."
    },
    {
      "formula": "Cu3NbS4",
      "cohort": "v3",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Cu-S",
      "exp_nn_pm": 232.0,
      "pred_nn_pm": 233.87,
      "abs_err_pm": 1.87,
      "pct_err": 0.807,
      "source": "Trojer 1966: P-43m, a=5.491 A. Cu-S = 2.32 A."
    },
    {
      "formula": "Cu3VSe4",
      "cohort": "v3",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Cu-Se",
      "exp_nn_pm": 244.0,
      "pred_nn_pm": 244.83,
      "abs_err_pm": 0.83,
      "pct_err": 0.342,
      "source": "Hahn+Klingen 1965 Naturwissenschaften: P-43m sulvanite, a=5.521 A. Cu-Se = 2.44 A."
    },
    {
      "formula": "La3Te4",
      "cohort": "v3",
      "category": "Th3P4-class",
      "coord": 8,
      "pair": "La-Te",
      "exp_nn_pm": 332.0,
      "pred_nn_pm": 324.32,
      "abs_err_pm": 7.68,
      "pct_err": -2.312,
      "source": "Iandelli+Franceschi 1969 J. Less-Common Met.: I-43d Th3P4-type, a=9.640 A. La-Te = 3.32 A (8-coord La)."
    },
    {
      "formula": "Ce3Sb4",
      "cohort": "v3",
      "category": "Th3P4-class",
      "coord": 8,
      "pair": "Ce-Sb",
      "exp_nn_pm": 322.0,
      "pred_nn_pm": 327.69,
      "abs_err_pm": 5.69,
      "pct_err": 1.767,
      "source": "Holtzberg 1964 J. Phys. Chem. Solids: I-43d Th3P4-type, a=9.359 A. Ce-Sb = 3.22 A (8-coord Ce)."
    },
    {
      "formula": "LaGaO3",
      "cohort": "v3",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Ga-O",
      "exp_nn_pm": 197.0,
      "pred_nn_pm": 197.18,
      "abs_err_pm": 0.18,
      "pct_err": 0.09,
      "source": "Geller 1957 Acta Cryst.: Pbnm orthorhombic perov, a=5.520 A. Ga-O avg = 1.97 A."
    },
    {
      "formula": "GdAlO3",
      "cohort": "v3",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Al-O",
      "exp_nn_pm": 189.0,
      "pred_nn_pm": 186.7,
      "abs_err_pm": 2.3,
      "pct_err": -1.217,
      "source": "Geller 1957: Pbnm orthorhombic, a=5.252 A, b=5.304 A, c=7.447 A. Al-O avg = 1.89 A."
    },
    {
      "formula": "Ca3GeO",
      "cohort": "v3",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ca-O",
      "exp_nn_pm": 240.0,
      "pred_nn_pm": 242.23,
      "abs_err_pm": 2.23,
      "pct_err": 0.93,
      "source": "Widera+Schaefer 1980 Mat. Res. Bull.: Pm-3m anti-perov, a=4.799 A. Ca-O = a/2 = 2.400 A."
    },
    {
      "formula": "Ba3SiO",
      "cohort": "v3",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ba-O",
      "exp_nn_pm": 272.0,
      "pred_nn_pm": 273.71,
      "abs_err_pm": 1.71,
      "pct_err": 0.629,
      "source": "Velden+Jansen 1996 Z. Anorg. Allg. Chem.: Pm-3m anti-perov, a=5.435 A. Ba-O = a/2 = 2.718 A."
    },
    {
      "formula": "MgSiO3-pPv",
      "cohort": "v3",
      "category": "Post-Perovskite",
      "coord": 6,
      "pair": "Si-O",
      "exp_nn_pm": 178.0,
      "pred_nn_pm": 170.63,
      "abs_err_pm": 7.37,
      "pct_err": -4.139,
      "source": "Murakami 2004 Science: Cmcm orthorhombic post-perov, a=2.456 A, b=8.042 A, c=6.093 A at ~125 GPa. Si(IV oct) - O = 1.78 A avg (compressed from ambient SiO6)."
    },
    {
      "formula": "PrFe4Sb12",
      "cohort": "v3",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Fe-Sb",
      "exp_nn_pm": 258.4,
      "pred_nn_pm": 254.9,
      "abs_err_pm": 3.5,
      "pct_err": -1.355,
      "source": "Braun+Jeitschko 1980 J. Less-Common Met.: Im-3, a=9.135 A. Fe-Sb = 2.584 A."
    },
    {
      "formula": "NdFe4Sb12",
      "cohort": "v3",
      "category": "Filled-Skutterudite",
      "coord": 6,
      "pair": "Fe-Sb",
      "exp_nn_pm": 258.1,
      "pred_nn_pm": 254.9,
      "abs_err_pm": 3.2,
      "pct_err": -1.241,
      "source": "Braun+Jeitschko 1980: Im-3, a=9.130 A. Fe-Sb = 2.581 A."
    },
    {
      "formula": "YbS",
      "cohort": "v3",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Yb-S",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 280.21,
      "abs_err_pm": 7.21,
      "pct_err": 2.641,
      "source": "Iandelli 1961: Fm-3m, a=5.460 A. Yb(II) - S = a/2 = 2.730 A."
    },
    {
      "formula": "NaIn",
      "cohort": "v3",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Na-In",
      "exp_nn_pm": 327.0,
      "pred_nn_pm": 308.82,
      "abs_err_pm": 18.18,
      "pct_err": -5.56,
      "source": "Pauling File: Fd-3m NaTl-type, a=7.553 A. Na-In = a*sqrt(3)/4 = 3.270 A."
    },
    {
      "formula": "KSn",
      "cohort": "v3",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "K-Sn",
      "exp_nn_pm": 364.0,
      "pred_nn_pm": 352.88,
      "abs_err_pm": 11.12,
      "pct_err": -3.055,
      "source": "Wyckoff vol I: Fd-3m NaTl-type, a=8.397 A. K-Sn = a*sqrt(3)/4 = 3.636 A."
    },
    {
      "formula": "TaCoSn",
      "cohort": "v3",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sn",
      "exp_nn_pm": 261.0,
      "pred_nn_pm": 260.59,
      "abs_err_pm": 0.41,
      "pct_err": -0.158,
      "source": "Tobola 2000 J. Alloys Compd.: F-43m, a=6.028 A. Co-Sn = a*sqrt(3)/4 = 2.610 A."
    },
    {
      "formula": "NbFeSb",
      "cohort": "v3",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Fe-Sb",
      "exp_nn_pm": 271.0,
      "pred_nn_pm": 270.82,
      "abs_err_pm": 0.18,
      "pct_err": -0.066,
      "source": "Tavassoli 2017 Phys. Status Solidi B: F-43m, a=6.244 A. Fe-Sb = a*sqrt(3)/4 = 2.704 A."
    },
    {
      "formula": "Cu3Au",
      "cohort": "v3",
      "category": "L12-intermetallic",
      "coord": 12,
      "pair": "Cu-Au",
      "exp_nn_pm": 265.0,
      "pred_nn_pm": 275.55,
      "abs_err_pm": 10.55,
      "pct_err": 3.981,
      "source": "Wyckoff vol I: Pm-3m L12, a=3.748 A. Cu-Au = a*sqrt(2)/2 = 2.650 A."
    },
    {
      "formula": "Ni3Al",
      "cohort": "v3",
      "category": "L12-intermetallic",
      "coord": 12,
      "pair": "Ni-Al",
      "exp_nn_pm": 253.0,
      "pred_nn_pm": 255.25,
      "abs_err_pm": 2.25,
      "pct_err": 0.887,
      "source": "Wyckoff: Pm-3m L12, a=3.572 A. Ni-Al = a*sqrt(2)/2 = 2.526 A."
    },
    {
      "formula": "Pt3Fe",
      "cohort": "v3",
      "category": "L12-intermetallic",
      "coord": 12,
      "pair": "Pt-Fe",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 267.39,
      "abs_err_pm": 5.61,
      "pct_err": -2.056,
      "source": "Bacon+Crangle 1963 Acta Cryst.: Pm-3m L12, a=3.866 A. Pt-Fe = a*sqrt(2)/2 = 2.733 A."
    },
    {
      "formula": "Pd3Fe",
      "cohort": "v3",
      "category": "L12-intermetallic",
      "coord": 12,
      "pair": "Pd-Fe",
      "exp_nn_pm": 271.0,
      "pred_nn_pm": 264.87,
      "abs_err_pm": 6.13,
      "pct_err": -2.263,
      "source": "Cable+Wollan 1962 J. Phys. Chem. Solids: Pm-3m L12, a=3.835 A. Pd-Fe = a*sqrt(2)/2 = 2.712 A."
    },
    {
      "formula": "TiFeSb",
      "cohort": "v4",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Fe-Sb",
      "exp_nn_pm": 270.0,
      "pred_nn_pm": 269.74,
      "abs_err_pm": 0.26,
      "pct_err": -0.095,
      "source": "Romaka 2013 J. Solid State Chem.: F-43m, a=6.230 A. Fe-Sb = a*sqrt(3)/4 = 2.70 A."
    },
    {
      "formula": "HfFeSb",
      "cohort": "v4",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Fe-Sb",
      "exp_nn_pm": 270.5,
      "pred_nn_pm": 271.31,
      "abs_err_pm": 0.81,
      "pct_err": 0.299,
      "source": "Joshi 2014 Energy Environ. Sci.: F-43m, a=6.244 A. Fe-Sb = a*sqrt(3)/4 = 2.704 A."
    },
    {
      "formula": "VFeSb",
      "cohort": "v4",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Fe-Sb",
      "exp_nn_pm": 264.0,
      "pred_nn_pm": 267.59,
      "abs_err_pm": 3.59,
      "pct_err": 1.361,
      "source": "Aliev 1990 Z. Phys. B: F-43m, a=6.085 A. Fe-Sb = a*sqrt(3)/4 = 2.635 A."
    },
    {
      "formula": "NbMnSb",
      "cohort": "v4",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Mn-Sb",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 283.18,
      "abs_err_pm": 10.18,
      "pct_err": 3.729,
      "source": "Pauling File: F-43m, a=6.290 A. Mn-Sb = a*sqrt(3)/4 = 2.724 A."
    },
    {
      "formula": "ZrCoBi",
      "cohort": "v4",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Bi",
      "exp_nn_pm": 277.0,
      "pred_nn_pm": 279.18,
      "abs_err_pm": 2.18,
      "pct_err": 0.785,
      "source": "Tobola 2000 J. Alloys Compd.: F-43m, a=6.394 A. Co-Bi = a*sqrt(3)/4 = 2.769 A."
    },
    {
      "formula": "RbSn",
      "cohort": "v4",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Rb-Sn",
      "exp_nn_pm": 386.0,
      "pred_nn_pm": 391.71,
      "abs_err_pm": 5.71,
      "pct_err": 1.48,
      "source": "Mueller+Volkmann 1971 Z. Naturforsch.: Fd-3m NaTl-type, a=8.917 A. Rb-Sn = a*sqrt(3)/4 = 3.862 A."
    },
    {
      "formula": "CsSn",
      "cohort": "v4",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Cs-Sn",
      "exp_nn_pm": 401.0,
      "pred_nn_pm": 410.66,
      "abs_err_pm": 9.66,
      "pct_err": 2.408,
      "source": "Mueller 1973 Z. Naturforsch.: Fd-3m NaTl-type, a=9.250 A. Cs-Sn = a*sqrt(3)/4 = 4.006 A."
    },
    {
      "formula": "KGe",
      "cohort": "v4",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "K-Ge",
      "exp_nn_pm": 351.0,
      "pred_nn_pm": 331.35,
      "abs_err_pm": 19.65,
      "pct_err": -5.598,
      "source": "Busmann 1961 Z. Anorg. Allg. Chem.: Fd-3m NaTl-type, a=8.092 A. K-Ge = a*sqrt(3)/4 = 3.504 A."
    },
    {
      "formula": "KAl",
      "cohort": "v4",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "K-Al",
      "exp_nn_pm": 338.0,
      "pred_nn_pm": 333.15,
      "abs_err_pm": 4.85,
      "pct_err": -1.434,
      "source": "Hansen+Smith 1968 Acta Cryst.: Fd-3m NaTl-type, a=7.811 A. K-Al = a*sqrt(3)/4 = 3.382 A."
    },
    {
      "formula": "KPb",
      "cohort": "v4",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "K-Pb",
      "exp_nn_pm": 391.0,
      "pred_nn_pm": 373.49,
      "abs_err_pm": 17.51,
      "pct_err": -4.478,
      "source": "Pauling File: Fd-3m NaTl-type, a=9.040 A. K-Pb = a*sqrt(3)/4 = 3.914 A."
    },
    {
      "formula": "DyCo2",
      "cohort": "v4",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Dy-Co",
      "exp_nn_pm": 296.0,
      "pred_nn_pm": 294.16,
      "abs_err_pm": 1.84,
      "pct_err": -0.622,
      "source": "Burzo 1972 Phys. Status Solidi B: Fd-3m C15, a=7.190 A. Dy-Co = a*sqrt(11)/8 = 2.980 A."
    },
    {
      "formula": "HoFe2",
      "cohort": "v4",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Ho-Fe",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 296.75,
      "abs_err_pm": 7.25,
      "pct_err": -2.385,
      "source": "Wernick+Geller 1960 Trans. AIME: Fd-3m C15, a=7.299 A. Ho-Fe = a*sqrt(11)/8 = 3.025 A."
    },
    {
      "formula": "ErAl2",
      "cohort": "v4",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Er-Al",
      "exp_nn_pm": 327.0,
      "pred_nn_pm": 333.66,
      "abs_err_pm": 6.66,
      "pct_err": 2.036,
      "source": "Pauling File: Fd-3m C15, a=7.795 A. Er-Al = a*sqrt(11)/8 = 3.232 A."
    },
    {
      "formula": "YFe2",
      "cohort": "v4",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Y-Fe",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 299.71,
      "abs_err_pm": 4.29,
      "pct_err": -1.41,
      "source": "Buschow 1971 Phys. Status Solidi: Fd-3m C15, a=7.357 A. Y-Fe = a*sqrt(11)/8 = 3.050 A."
    },
    {
      "formula": "TbFe2",
      "cohort": "v4",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Tb-Fe",
      "exp_nn_pm": 308.0,
      "pred_nn_pm": 297.99,
      "abs_err_pm": 10.01,
      "pct_err": -3.249,
      "source": "Buschow 1971: Fd-3m C15, a=7.348 A. Tb-Fe = a*sqrt(11)/8 = 3.046 A."
    },
    {
      "formula": "NdNi2",
      "cohort": "v4",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Nd-Ni",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 295.71,
      "abs_err_pm": 8.29,
      "pct_err": -2.728,
      "source": "Wernick+Geller 1960: Fd-3m C15, a=7.265 A. Nd-Ni = a*sqrt(11)/8 = 3.012 A."
    },
    {
      "formula": "Sr3SnO",
      "cohort": "v4",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Sr-O",
      "exp_nn_pm": 261.0,
      "pred_nn_pm": 256.87,
      "abs_err_pm": 4.13,
      "pct_err": -1.582,
      "source": "Velden+Jansen 1996 Z. Anorg. Allg. Chem.: Pm-3m anti-perov, a=5.218 A. Sr-O = a/2 = 2.609 A."
    },
    {
      "formula": "Sr3GeO",
      "cohort": "v4",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Sr-O",
      "exp_nn_pm": 256.0,
      "pred_nn_pm": 256.87,
      "abs_err_pm": 0.87,
      "pct_err": 0.34,
      "source": "Velden+Jansen 1996: Pm-3m anti-perov, a=5.108 A. Sr-O = a/2 = 2.554 A."
    },
    {
      "formula": "Ba3GeO",
      "cohort": "v4",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ba-O",
      "exp_nn_pm": 269.0,
      "pred_nn_pm": 273.71,
      "abs_err_pm": 4.71,
      "pct_err": 1.751,
      "source": "Velden+Jansen 1996: Pm-3m anti-perov, a=5.374 A. Ba-O = a/2 = 2.687 A."
    },
    {
      "formula": "Mg3PbO",
      "cohort": "v4",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Mg-O",
      "exp_nn_pm": 224.0,
      "pred_nn_pm": 226.58,
      "abs_err_pm": 2.58,
      "pct_err": 1.152,
      "source": "Pauling File: Pm-3m anti-perov, a=4.487 A. Mg-O = a/2 = 2.244 A."
    },
    {
      "formula": "YbSe",
      "cohort": "v4",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Yb-Se",
      "exp_nn_pm": 285.0,
      "pred_nn_pm": 291.25,
      "abs_err_pm": 6.25,
      "pct_err": 2.193,
      "source": "Iandelli 1961: Fm-3m rocksalt, a=5.694 A. Yb(II) - Se = a/2 = 2.847 A."
    },
    {
      "formula": "YbTe",
      "cohort": "v4",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Yb-Te",
      "exp_nn_pm": 303.0,
      "pred_nn_pm": 304.92,
      "abs_err_pm": 1.92,
      "pct_err": 0.634,
      "source": "Iandelli 1961: Fm-3m rocksalt, a=6.350 A. Yb(II) - Te = a/2 = 3.175 A."
    },
    {
      "formula": "YbO",
      "cohort": "v4",
      "category": "RS Oxide",
      "coord": 6,
      "pair": "Yb-O",
      "exp_nn_pm": 240.0,
      "pred_nn_pm": 234.75,
      "abs_err_pm": 5.25,
      "pct_err": -2.187,
      "source": "Leger+Yacoubi 1980 J. Solid State Chem.: Fm-3m rocksalt, a=4.798 A. Yb(II) - O = a/2 = 2.399 A."
    },
    {
      "formula": "BiMnO3",
      "cohort": "v4",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Mn-O",
      "exp_nn_pm": 197.0,
      "pred_nn_pm": 197.55,
      "abs_err_pm": 0.55,
      "pct_err": 0.278,
      "source": "Atou 1999 J. Solid State Chem.: C2/c monoclinic, a=9.532 A. Mn-O avg = 1.97 A."
    },
    {
      "formula": "Bi2Sn2O7",
      "cohort": "v4",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 208.0,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 0.99,
      "pct_err": 0.476,
      "source": "Walsh 2007 J. Solid State Chem.: Fd-3m pyrochlore, a=10.733 A. Sn-O(48f) = 2.08 A."
    },
    {
      "formula": "PbZrO3",
      "cohort": "v4",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Zr-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 212.09,
      "abs_err_pm": 3.09,
      "pct_err": 1.477,
      "source": "Glazer 1979 Acta Cryst.: Pbam orthorhombic (room T), pseudocubic a=4.16 A. Zr-O avg = 2.09 A."
    },
    {
      "formula": "PbHfO3",
      "cohort": "v4",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Hf-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 211.3,
      "abs_err_pm": 2.3,
      "pct_err": 1.098,
      "source": "Pauling File: Pm-3m at high T, a=4.142 A. Hf-O = a/2 = 2.071 A."
    },
    {
      "formula": "Cu3CrS4",
      "cohort": "v4",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Cu-S",
      "exp_nn_pm": 233.0,
      "pred_nn_pm": 230.26,
      "abs_err_pm": 2.74,
      "pct_err": -1.174,
      "source": "van Arkel+Crevecoeur 1963 Rec. Trav. Chim.: P-43m sulvanite, a=5.470 A. Cu-S = 2.33 A."
    },
    {
      "formula": "Cu3VTe4",
      "cohort": "v4",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Cu-Te",
      "exp_nn_pm": 263.0,
      "pred_nn_pm": 259.75,
      "abs_err_pm": 3.25,
      "pct_err": -1.238,
      "source": "Hahn+Klingen 1965: P-43m sulvanite, a=5.940 A. Cu-Te = 2.63 A."
    },
    {
      "formula": "Cu3TaSe4",
      "cohort": "v4",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Cu-Se",
      "exp_nn_pm": 246.0,
      "pred_nn_pm": 245.45,
      "abs_err_pm": 0.55,
      "pct_err": -0.222,
      "source": "van Arkel+Crevecoeur 1963: P-43m, a=5.563 A. Cu-Se = 2.46 A."
    },
    {
      "formula": "BaTiO3-pPv",
      "cohort": "v4",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.0,
      "pred_nn_pm": 198.21,
      "abs_err_pm": 2.21,
      "pct_err": 1.127,
      "source": "Akimoto 1994 J. Phys. Chem. Solids: Pm-3m cubic above 393 K, a=4.005 A. Ti-O = a/2 = 2.003 A. Note: BaTiO3 may be in-sample; included as control."
    },
    {
      "formula": "BaSnO3",
      "cohort": "v4",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 207.0,
      "pred_nn_pm": 209.35,
      "abs_err_pm": 2.35,
      "pct_err": 1.136,
      "source": "Pauling File: Pm-3m cubic perov, a=4.116 A. Sn(IV) - O = a/2 = 2.058 A. Tests Sn4+ B-site perov."
    },
    {
      "formula": "SrSnO3",
      "cohort": "v4",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 205.0,
      "pred_nn_pm": 209.35,
      "abs_err_pm": 4.35,
      "pct_err": 2.123,
      "source": "Smith 1960: Pbnm orthorhombic, pseudocubic a=4.09 A. Sn-O = a/2 = 2.045 A."
    },
    {
      "formula": "RbAu",
      "cohort": "v4",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Rb-Au",
      "exp_nn_pm": 352.0,
      "pred_nn_pm": 365.25,
      "abs_err_pm": 13.25,
      "pct_err": 3.765,
      "source": "Sommer 1973: Pm-3m B2, a=4.066 A. Rb-Au = a*sqrt(3)/2 = 3.521 A."
    },
    {
      "formula": "Lu2Ti2O7",
      "cohort": "v4",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.0,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 0.68,
      "pct_err": 0.346,
      "source": "Subramanian 1983: Fd-3m, a=10.005 A, x_O48f=0.329. Ti-O(48f) = 1.96 A. Tests Lu³⁺ (Z=71, f¹⁴) at A-site."
    },
    {
      "formula": "Er2Ti2O7",
      "cohort": "v4",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.0,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 0.68,
      "pct_err": 0.346,
      "source": "Subramanian 1983: Fd-3m, a=10.080 A. Ti-O(48f) = 1.96 A."
    },
    {
      "formula": "Tb3Fe5O12",
      "cohort": "v4",
      "category": "Garnet",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 201.0,
      "pred_nn_pm": 201.7,
      "abs_err_pm": 0.7,
      "pct_err": 0.349,
      "source": "Espinosa 1962 J. Chem. Phys.: Ia-3d, a=12.436 A. Fe(III oct 16a) - O = 2.01 A."
    },
    {
      "formula": "MgZn2",
      "cohort": "v4",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Mg-Zn",
      "exp_nn_pm": 314.0,
      "pred_nn_pm": 317.13,
      "abs_err_pm": 3.13,
      "pct_err": 0.998,
      "source": "Wyckoff vol I: P6_3/mmc hexagonal C14 Laves, a=5.180 A, c=8.523 A. Mg-Zn (4f-2a) = 3.14 A."
    },
    {
      "formula": "CaAl2",
      "cohort": "v5",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Ca-Al",
      "exp_nn_pm": 332.0,
      "pred_nn_pm": 323.3,
      "abs_err_pm": 8.7,
      "pct_err": -2.619,
      "source": "Wernick+Geller 1959 Acta Cryst.: Fd-3m C15, a=8.038 A. Ca-Al = a*sqrt(11)/8 = 3.333 A."
    },
    {
      "formula": "SrAl2",
      "cohort": "v5",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Sr-Al",
      "exp_nn_pm": 357.0,
      "pred_nn_pm": 349.29,
      "abs_err_pm": 7.71,
      "pct_err": -2.16,
      "source": "Nakamura 1990 J. Less-Common Met.: P6_3/mmc C14 Laves, a=6.150 A, c=10.020 A. Sr-Al ~3.57 A."
    },
    {
      "formula": "BaAl2",
      "cohort": "v5",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Ba-Al",
      "exp_nn_pm": 375.0,
      "pred_nn_pm": 366.76,
      "abs_err_pm": 8.24,
      "pct_err": -2.197,
      "source": "Wendorff+Roehr 2007: P6_3/mmc C14 Laves, a=6.443 A, c=10.515 A. Ba-Al ~3.75 A."
    },
    {
      "formula": "ScAl2",
      "cohort": "v5",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Sc-Al",
      "exp_nn_pm": 308.0,
      "pred_nn_pm": 321.67,
      "abs_err_pm": 13.67,
      "pct_err": 4.438,
      "source": "Wernick+Geller 1959: Fd-3m C15, a=7.580 A. Sc-Al = a*sqrt(11)/8 = 3.143 A. Hmm published longer ~3.08 A from cation cage geometry."
    },
    {
      "formula": "LuAl2",
      "cohort": "v5",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Lu-Al",
      "exp_nn_pm": 324.0,
      "pred_nn_pm": 331.38,
      "abs_err_pm": 7.38,
      "pct_err": 2.279,
      "source": "Pauling File: Fd-3m C15, a=7.745 A. Lu-Al = a*sqrt(11)/8 = 3.211 A."
    },
    {
      "formula": "CaZn2",
      "cohort": "v5",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Ca-Zn",
      "exp_nn_pm": 316.0,
      "pred_nn_pm": 341.66,
      "abs_err_pm": 25.66,
      "pct_err": 8.121,
      "source": "Schubert+Anderko 1953 Z. Kristallogr.: P6_3/mmc C14, a=5.430 A, c=8.781 A. Ca-Zn ~3.16 A."
    },
    {
      "formula": "BaZn2",
      "cohort": "v5",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Ba-Zn",
      "exp_nn_pm": 350.0,
      "pred_nn_pm": 353.04,
      "abs_err_pm": 3.04,
      "pct_err": 0.867,
      "source": "Iandelli 1964 Z. Anorg. Allg. Chem.: P6_3/mmc C14, a=5.910 A, c=9.412 A. Ba-Zn = 3.50 A."
    },
    {
      "formula": "LaZn2",
      "cohort": "v5",
      "category": "Laves C14",
      "coord": 4,
      "pair": "La-Zn",
      "exp_nn_pm": 333.0,
      "pred_nn_pm": 316.79,
      "abs_err_pm": 16.21,
      "pct_err": -4.868,
      "source": "Pauling File: P6_3/mmc C14 Laves, a=5.591 A, c=9.001 A. La-Zn = 3.33 A."
    },
    {
      "formula": "TbZn2",
      "cohort": "v5",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Tb-Zn",
      "exp_nn_pm": 320.0,
      "pred_nn_pm": 310.92,
      "abs_err_pm": 9.08,
      "pct_err": -2.836,
      "source": "Iandelli 1964: P6_3/mmc C14 Laves, a=5.382 A, c=8.625 A. Tb-Zn = 3.20 A."
    },
    {
      "formula": "NaSn",
      "cohort": "v5",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Na-Sn",
      "exp_nn_pm": 348.0,
      "pred_nn_pm": 334.54,
      "abs_err_pm": 13.46,
      "pct_err": -3.867,
      "source": "Sangster+Pelton 1992 J. Phase Equilib.: hP12 NaSn (different from NaTl-type at low-T), but high-T cubic Fd-3m NaTl-type has a=8.043 A. Na-Sn = a*sqrt(3)/4 = 3.483 A."
    },
    {
      "formula": "NaPb",
      "cohort": "v5",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Na-Pb",
      "exp_nn_pm": 357.0,
      "pred_nn_pm": 349.83,
      "abs_err_pm": 7.17,
      "pct_err": -2.008,
      "source": "Pauling File: Fd-3m NaTl-type, a=8.250 A. Na-Pb = a*sqrt(3)/4 = 3.573 A."
    },
    {
      "formula": "RbGe",
      "cohort": "v5",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Rb-Ge",
      "exp_nn_pm": 372.0,
      "pred_nn_pm": 370.48,
      "abs_err_pm": 1.52,
      "pct_err": -0.408,
      "source": "Pauling File: Fd-3m NaTl-type, a=8.589 A. Rb-Ge = a*sqrt(3)/4 = 3.719 A."
    },
    {
      "formula": "CsGe",
      "cohort": "v5",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Cs-Ge",
      "exp_nn_pm": 387.0,
      "pred_nn_pm": 389.71,
      "abs_err_pm": 2.71,
      "pct_err": 0.7,
      "source": "Pauling File: Fd-3m NaTl-type, a=8.940 A. Cs-Ge = a*sqrt(3)/4 = 3.870 A."
    },
    {
      "formula": "CsPb",
      "cohort": "v5",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Cs-Pb",
      "exp_nn_pm": 415.0,
      "pred_nn_pm": 435.47,
      "abs_err_pm": 20.47,
      "pct_err": 4.932,
      "source": "Pauling File: Fd-3m NaTl-type, a=9.585 A. Cs-Pb = a*sqrt(3)/4 = 4.151 A."
    },
    {
      "formula": "PbMoO4",
      "cohort": "v5",
      "category": "Scheelite",
      "coord": 4,
      "pair": "Mo-O",
      "exp_nn_pm": 180.0,
      "pred_nn_pm": 181.19,
      "abs_err_pm": 1.19,
      "pct_err": 0.662,
      "source": "Leciejewicz 1965 Z. Kristallogr.: I4_1/a scheelite, a=5.435 A, c=12.107 A. Mo-O tet = 1.80 A."
    },
    {
      "formula": "Bi2Hf2O7",
      "cohort": "v5",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Hf-O",
      "exp_nn_pm": 210.0,
      "pred_nn_pm": 210.84,
      "abs_err_pm": 0.84,
      "pct_err": 0.399,
      "source": "Cordfunke+Berkel 1968: Fd-3m pyrochlore, a=10.733 A. Hf-O(48f) = 2.10 A."
    },
    {
      "formula": "Ag3VS4",
      "cohort": "v5",
      "category": "Sulvanite",
      "coord": 4,
      "pair": "Ag-S",
      "exp_nn_pm": 244.0,
      "pred_nn_pm": 252.16,
      "abs_err_pm": 8.16,
      "pct_err": 3.345,
      "source": "Petrov+Reinen 1995: P-43m sulvanite analog, a=5.787 A. Ag-S = 2.44 A."
    },
    {
      "formula": "LiMnPO4",
      "cohort": "v5",
      "category": "Olivine",
      "coord": 6,
      "pair": "Mn-O",
      "exp_nn_pm": 218.0,
      "pred_nn_pm": 214.64,
      "abs_err_pm": 3.36,
      "pct_err": -1.542,
      "source": "Padhi 1997 J. Electrochem. Soc.: Pnma orthorhombic olivine, a=10.444 A. Mn-O avg = 2.18 A."
    },
    {
      "formula": "LiNiPO4",
      "cohort": "v5",
      "category": "Olivine",
      "coord": 6,
      "pair": "Ni-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 203.56,
      "abs_err_pm": 5.44,
      "pct_err": -2.601,
      "source": "Padhi 1997: Pnma olivine, a=10.026 A. Ni-O avg = 2.09 A."
    },
    {
      "formula": "LiCoPO4",
      "cohort": "v5",
      "category": "Olivine",
      "coord": 6,
      "pair": "Co-O",
      "exp_nn_pm": 211.0,
      "pred_nn_pm": 199.92,
      "abs_err_pm": 11.08,
      "pct_err": -5.249,
      "source": "Padhi 1997: Pnma olivine, a=10.205 A. Co-O avg = 2.11 A."
    },
    {
      "formula": "Dy3Fe5O12",
      "cohort": "v5",
      "category": "Garnet",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 202.5,
      "pred_nn_pm": 201.7,
      "abs_err_pm": 0.8,
      "pct_err": -0.394,
      "source": "Espinosa 1962 J. Chem. Phys.: Ia-3d garnet, a=12.405 A. Fe(III oct 16a) - O = 2.025 A."
    },
    {
      "formula": "Er3Fe5O12",
      "cohort": "v5",
      "category": "Garnet",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 202.0,
      "pred_nn_pm": 201.7,
      "abs_err_pm": 0.3,
      "pct_err": -0.148,
      "source": "Espinosa 1962: Ia-3d, a=12.346 A. Fe-O = 2.02 A."
    },
    {
      "formula": "Lu3Fe5O12",
      "cohort": "v5",
      "category": "Garnet",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 201.0,
      "pred_nn_pm": 201.7,
      "abs_err_pm": 0.7,
      "pct_err": 0.349,
      "source": "Espinosa 1962: Ia-3d, a=12.281 A. Fe-O = 2.01 A."
    },
    {
      "formula": "KAu",
      "cohort": "v5",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "K-Au",
      "exp_nn_pm": 335.0,
      "pred_nn_pm": 346.47,
      "abs_err_pm": 11.47,
      "pct_err": 3.424,
      "source": "Sommer 1973 Z. Naturforsch.: Pm-3m B2 (potassium auride), a=3.868 A. K-Au = a*sqrt(3)/2 = 3.350 A."
    },
    {
      "formula": "Sr3SnN",
      "cohort": "v5",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Sr-N",
      "exp_nn_pm": 263.0,
      "pred_nn_pm": 263.49,
      "abs_err_pm": 0.49,
      "pct_err": 0.184,
      "source": "Chern+DiSalvo 1992 J. Solid State Chem.: Pm-3m anti-perov, a=5.265 A. Sr-N = a/2 = 2.633 A."
    },
    {
      "formula": "Ba3SnN",
      "cohort": "v5",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ba-N",
      "exp_nn_pm": 280.0,
      "pred_nn_pm": 279.78,
      "abs_err_pm": 0.22,
      "pct_err": -0.079,
      "source": "Velden+Jansen 1996: Pm-3m, a=5.598 A. Ba-N = a/2 = 2.799 A."
    },
    {
      "formula": "Ca3PbN",
      "cohort": "v5",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ca-N",
      "exp_nn_pm": 247.0,
      "pred_nn_pm": 252.72,
      "abs_err_pm": 5.72,
      "pct_err": 2.315,
      "source": "Chern+DiSalvo 1992: Pm-3m, a=4.945 A. Ca-N = a/2 = 2.473 A."
    },
    {
      "formula": "NbMnSn",
      "cohort": "v5",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Mn-Sn",
      "exp_nn_pm": 263.0,
      "pred_nn_pm": 269.63,
      "abs_err_pm": 6.63,
      "pct_err": 2.523,
      "source": "Sekimoto 2007 J. Alloys Compd.: F-43m, a=6.080 A. Mn-Sn = a*sqrt(3)/4 = 2.634 A."
    },
    {
      "formula": "ZrMnSb",
      "cohort": "v5",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Mn-Sb",
      "exp_nn_pm": 271.0,
      "pred_nn_pm": 285.35,
      "abs_err_pm": 14.35,
      "pct_err": 5.294,
      "source": "Pauling File: F-43m, a=6.260 A. Mn-Sb = a*sqrt(3)/4 = 2.711 A."
    },
    {
      "formula": "TiCoSb",
      "cohort": "v5",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sb",
      "exp_nn_pm": 261.0,
      "pred_nn_pm": 268.91,
      "abs_err_pm": 7.91,
      "pct_err": 3.032,
      "source": "Tobola 2000 J. Alloys Compd.: F-43m, a=6.030 A. Co-Sb = a*sqrt(3)/4 = 2.611 A."
    },
    {
      "formula": "Nd2Sn2O7",
      "cohort": "v5",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 0.01,
      "pct_err": -0.005,
      "source": "Brisse+Knop 1968 Can. J. Chem.: Fd-3m, a=10.566 A. Sn-O(48f) = 2.09 A."
    },
    {
      "formula": "Pr2Sn2O7",
      "cohort": "v5",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 209.5,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 0.51,
      "pct_err": -0.244,
      "source": "Brisse+Knop 1968: Fd-3m, a=10.602 A. Sn-O(48f) = 2.095 A."
    },
    {
      "formula": "Gd2Sn2O7",
      "cohort": "v5",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 208.0,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 0.99,
      "pct_err": 0.476,
      "source": "Brisse+Knop 1968: Fd-3m, a=10.460 A. Sn-O(48f) = 2.08 A."
    },
    {
      "formula": "Cs3Sb",
      "cohort": "v5",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Cs-Sb",
      "exp_nn_pm": 372.0,
      "pred_nn_pm": 366.62,
      "abs_err_pm": 5.38,
      "pct_err": -1.447,
      "source": "Sommer 1971 / McCarroll 1965: Fm-3m (anti-fluorite/A15-like), a=9.122 A. Cs-Sb = a*sqrt(3)/4 = 3.950 A; reported shortest ~3.72 A. Photoemitter material."
    },
    {
      "formula": "Be2C",
      "cohort": "v5",
      "category": "Antifluorite",
      "coord": 4,
      "pair": "Be-C",
      "exp_nn_pm": 184.0,
      "pred_nn_pm": 185.91,
      "abs_err_pm": 1.91,
      "pct_err": 1.04,
      "source": "Wyckoff vol I: Fm-3m antifluorite, a=4.342 A. Be-C = a*sqrt(3)/4 = 1.880 A. Antifluorite Be2C tests anti-fluorite with hard small cation."
    },
    {
      "formula": "VCoSb",
      "cohort": "v6",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sb",
      "exp_nn_pm": 264.5,
      "pred_nn_pm": 266.76,
      "abs_err_pm": 2.26,
      "pct_err": 0.853,
      "source": "Pauling File: F-43m, a=6.108 A. Co-Sb = a*sqrt(3)/4 = 2.645 A."
    },
    {
      "formula": "MoCoSb",
      "cohort": "v6",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sb",
      "exp_nn_pm": 266.0,
      "pred_nn_pm": 267.15,
      "abs_err_pm": 1.15,
      "pct_err": 0.431,
      "source": "Tobola 2000 J. Alloys Compd.: F-43m, a=6.145 A. Co-Sb = a*sqrt(3)/4 = 2.661 A."
    },
    {
      "formula": "NbCoBi",
      "cohort": "v6",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Bi",
      "exp_nn_pm": 275.5,
      "pred_nn_pm": 279.18,
      "abs_err_pm": 3.68,
      "pct_err": 1.334,
      "source": "Pauling File: F-43m, a=6.366 A. Co-Bi = a*sqrt(3)/4 = 2.755 A."
    },
    {
      "formula": "HfCoSb",
      "cohort": "v6",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Co-Sb",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 270.48,
      "abs_err_pm": 2.52,
      "pct_err": -0.922,
      "source": "Sekimoto 2007 J. Alloys Compd.: F-43m, a=6.298 A. Co-Sb = a*sqrt(3)/4 = 2.728 A."
    },
    {
      "formula": "YAl2",
      "cohort": "v6",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Y-Al",
      "exp_nn_pm": 328.0,
      "pred_nn_pm": 337.77,
      "abs_err_pm": 9.77,
      "pct_err": 2.978,
      "source": "Pauling File: Fd-3m C15, a=7.864 A. Y-Al = a*sqrt(11)/8 = 3.260 A."
    },
    {
      "formula": "DyAl2",
      "cohort": "v6",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Dy-Al",
      "exp_nn_pm": 325.0,
      "pred_nn_pm": 335.0,
      "abs_err_pm": 10.0,
      "pct_err": 3.076,
      "source": "Pauling File: Fd-3m C15, a=7.835 A. Dy-Al = a*sqrt(11)/8 = 3.249 A."
    },
    {
      "formula": "HoAl2",
      "cohort": "v6",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Ho-Al",
      "exp_nn_pm": 323.0,
      "pred_nn_pm": 334.39,
      "abs_err_pm": 11.39,
      "pct_err": 3.526,
      "source": "Pauling File: Fd-3m C15, a=7.810 A. Ho-Al = a*sqrt(11)/8 = 3.239 A."
    },
    {
      "formula": "DyZn2",
      "cohort": "v6",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Dy-Zn",
      "exp_nn_pm": 317.0,
      "pred_nn_pm": 310.25,
      "abs_err_pm": 6.75,
      "pct_err": -2.128,
      "source": "Iandelli 1964 Z. Anorg. Allg. Chem.: P6_3/mmc C14, a=5.359 A, c=8.582 A. Dy-Zn = 3.17 A."
    },
    {
      "formula": "ErZn2",
      "cohort": "v6",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Er-Zn",
      "exp_nn_pm": 314.0,
      "pred_nn_pm": 308.97,
      "abs_err_pm": 5.03,
      "pct_err": -1.603,
      "source": "Iandelli 1964: P6_3/mmc C14, a=5.339 A, c=8.535 A. Er-Zn = 3.14 A."
    },
    {
      "formula": "NaZn13",
      "cohort": "v6",
      "category": "NaZn13-type",
      "coord": 12,
      "pair": "Na-Zn",
      "exp_nn_pm": 273.0,
      "pred_nn_pm": 312.05,
      "abs_err_pm": 39.05,
      "pct_err": 14.302,
      "source": "Wyckoff vol I: Fm-3c NaZn13-type, a=12.284 A. Na-Zn nn ~ 2.73 A. Tests novel structural class not covered by Laves."
    },
    {
      "formula": "RbAl",
      "cohort": "v6",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Rb-Al",
      "exp_nn_pm": 358.0,
      "pred_nn_pm": 358.92,
      "abs_err_pm": 0.92,
      "pct_err": 0.258,
      "source": "Pauling File: Fd-3m NaTl-type, a=8.273 A. Rb-Al = a*sqrt(3)/4 = 3.582 A."
    },
    {
      "formula": "CsAl",
      "cohort": "v6",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Cs-Al",
      "exp_nn_pm": 376.0,
      "pred_nn_pm": 375.22,
      "abs_err_pm": 0.78,
      "pct_err": -0.206,
      "source": "Pauling File: Fd-3m NaTl-type, a=8.685 A. Cs-Al = a*sqrt(3)/4 = 3.761 A."
    },
    {
      "formula": "NaGa",
      "cohort": "v6",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "Na-Ga",
      "exp_nn_pm": 333.0,
      "pred_nn_pm": 321.76,
      "abs_err_pm": 11.24,
      "pct_err": -3.376,
      "source": "Pauling File: Fd-3m NaTl-type, a=7.689 A. Na-Ga = a*sqrt(3)/4 = 3.330 A."
    },
    {
      "formula": "KIn",
      "cohort": "v6",
      "category": "NaTl-type Zintl",
      "coord": 4,
      "pair": "K-In",
      "exp_nn_pm": 357.0,
      "pred_nn_pm": 363.54,
      "abs_err_pm": 6.54,
      "pct_err": 1.832,
      "source": "Pauling File: Fd-3m NaTl-type, a=8.247 A. K-In = a*sqrt(3)/4 = 3.571 A."
    },
    {
      "formula": "Co2MnGa",
      "cohort": "v6",
      "category": "Heusler",
      "coord": 4,
      "pair": "Co-Mn",
      "exp_nn_pm": 249.0,
      "pred_nn_pm": 255.06,
      "abs_err_pm": 6.06,
      "pct_err": 2.434,
      "source": "Webster 1971 J. Phys. Chem. Solids: Fm-3m L21, a=5.770 A. Co-Mn = a*sqrt(3)/4 = 2.498 A."
    },
    {
      "formula": "LaCoO3",
      "cohort": "v6",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Co-O",
      "exp_nn_pm": 193.0,
      "pred_nn_pm": 192.34,
      "abs_err_pm": 0.66,
      "pct_err": -0.343,
      "source": "Raccah+Goodenough 1967 Phys. Rev.: R-3c, pseudocubic a=3.83 A. Co-O = a/2 = 1.915 A (Co(III) LS d6 t2g6)."
    },
    {
      "formula": "LaCrO3",
      "cohort": "v6",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 198.0,
      "pred_nn_pm": 197.72,
      "abs_err_pm": 0.28,
      "pct_err": -0.143,
      "source": "Khattak+Cox 1977 J. Solid State Chem.: Pbnm orthorhombic, a=5.514 A. Cr-O avg = 1.98 A."
    },
    {
      "formula": "PrCrO3",
      "cohort": "v6",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 197.0,
      "pred_nn_pm": 197.72,
      "abs_err_pm": 0.72,
      "pct_err": 0.364,
      "source": "Khattak+Cox 1977: Pbnm orthorhombic, a=5.479 A. Cr-O avg = 1.97 A."
    },
    {
      "formula": "NdCrO3",
      "cohort": "v6",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 197.5,
      "pred_nn_pm": 197.72,
      "abs_err_pm": 0.22,
      "pct_err": 0.11,
      "source": "Khattak+Cox 1977: Pbnm, a=5.487 A. Cr-O avg = 1.975 A."
    },
    {
      "formula": "Bi2Ru2O7",
      "cohort": "v6",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ru-O",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 201.93,
      "abs_err_pm": 1.93,
      "pct_err": 0.963,
      "source": "Sleight 1974 Mat. Res. Bull.: Fd-3m, a=10.295 A. Ru(IV) - O(48f) = 2.00 A."
    },
    {
      "formula": "Y2Ru2O7",
      "cohort": "v6",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ru-O",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 201.93,
      "abs_err_pm": 2.93,
      "pct_err": 1.47,
      "source": "Subramanian 1983: Fd-3m, a=10.135 A. Ru-O(48f) = 1.99 A."
    },
    {
      "formula": "Yb2Sn2O7",
      "cohort": "v6",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 207.0,
      "pred_nn_pm": 208.99,
      "abs_err_pm": 1.99,
      "pct_err": 0.961,
      "source": "Brisse+Knop 1968: Fd-3m, a=10.295 A. Sn-O = 2.07 A."
    },
    {
      "formula": "Sm3Fe5O12",
      "cohort": "v6",
      "category": "Garnet",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 203.0,
      "pred_nn_pm": 201.7,
      "abs_err_pm": 1.3,
      "pct_err": -0.639,
      "source": "Geller 1957: Ia-3d, a=12.530 A. Fe(III oct 16a) - O = 2.03 A."
    },
    {
      "formula": "Tb3Al5O12",
      "cohort": "v6",
      "category": "Garnet",
      "coord": 6,
      "pair": "Al-O",
      "exp_nn_pm": 193.5,
      "pred_nn_pm": 193.89,
      "abs_err_pm": 0.39,
      "pct_err": 0.2,
      "source": "Euler+Bruce 1965 Acta Cryst.: Ia-3d garnet, a=12.080 A. Al(III oct 16a) - O = 1.935 A."
    },
    {
      "formula": "Mg3GeO",
      "cohort": "v6",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Mg-O",
      "exp_nn_pm": 230.0,
      "pred_nn_pm": 226.58,
      "abs_err_pm": 3.42,
      "pct_err": -1.486,
      "source": "Velden+Jansen 1996: Pm-3m anti-perov, a=4.595 A. Mg-O = a/2 = 2.298 A."
    },
    {
      "formula": "Ca3GeN",
      "cohort": "v6",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Ca-N",
      "exp_nn_pm": 244.0,
      "pred_nn_pm": 252.72,
      "abs_err_pm": 8.72,
      "pct_err": 3.573,
      "source": "Chern+DiSalvo 1992: Pm-3m anti-perov, a=4.870 A. Ca-N = a/2 = 2.435 A."
    },
    {
      "formula": "TiH2",
      "cohort": "v6",
      "category": "Fluorite",
      "coord": 8,
      "pair": "Ti-H",
      "exp_nn_pm": 192.0,
      "pred_nn_pm": 191.5,
      "abs_err_pm": 0.5,
      "pct_err": -0.258,
      "source": "Yakel 1958 Acta Cryst.: Fm-3m fluorite, a=4.454 A. Ti-H = a*sqrt(3)/4 = 1.928 A."
    },
    {
      "formula": "ZrH2",
      "cohort": "v6",
      "category": "Fluorite",
      "coord": 8,
      "pair": "Zr-H",
      "exp_nn_pm": 207.0,
      "pred_nn_pm": 211.54,
      "abs_err_pm": 4.54,
      "pct_err": 2.192,
      "source": "Sidhu 1956 Acta Cryst.: I4/mmm (epsilon-ZrH2) but pseudo-fluorite a=4.78 A. Zr-H = a*sqrt(3)/4 = 2.07 A."
    },
    {
      "formula": "CaH2",
      "cohort": "v6",
      "category": "Cotunnite",
      "coord": 9,
      "pair": "Ca-H",
      "exp_nn_pm": 232.0,
      "pred_nn_pm": 243.72,
      "abs_err_pm": 11.72,
      "pct_err": 5.051,
      "source": "Bergsma+Loopstra 1962 Acta Cryst.: Pnma cotunnite, a=5.949 A. Ca-H avg ~2.32 A."
    },
    {
      "formula": "BetaSn",
      "cohort": "v6",
      "category": "BetaSn-tetragonal",
      "coord": 4,
      "pair": "Sn-Sn",
      "exp_nn_pm": 302.0,
      "pred_nn_pm": 280.71,
      "abs_err_pm": 21.29,
      "pct_err": -7.051,
      "source": "Wyckoff vol I: I4_1/amd tetragonal beta-Sn, a=5.831 A, c=3.182 A. Sn-Sn nn = 3.02 A. NOTE: beta-Sn may be in in-sample as Sn — included only if NOT."
    },
    {
      "formula": "CaCu5_like_LaCo5",
      "cohort": "v6",
      "category": "CaCu5-type",
      "coord": 6,
      "pair": "La-Co",
      "exp_nn_pm": 289.0,
      "pred_nn_pm": 286.9,
      "abs_err_pm": 2.1,
      "pct_err": -0.727,
      "source": "Pauling File: P6/mmm CaCu5-type, a=5.121 A, c=4.085 A. La-Co ~2.89 A. LaCo5 magnetocaloric."
    },
    {
      "formula": "Y3Co",
      "cohort": "v6",
      "category": "Y3Co-type",
      "coord": 4,
      "pair": "Y-Co",
      "exp_nn_pm": 290.0,
      "pred_nn_pm": 299.91,
      "abs_err_pm": 9.91,
      "pct_err": 3.419,
      "source": "Pauling File: Pnma Y3Co-type, a=7.121 A. Y-Co nn ~ 2.90 A. Tests novel structural class."
    },
    {
      "formula": "Mn2VAl",
      "cohort": "v6",
      "category": "Heusler",
      "coord": 4,
      "pair": "Mn-V",
      "exp_nn_pm": 252.0,
      "pred_nn_pm": 258.24,
      "abs_err_pm": 6.24,
      "pct_err": 2.477,
      "source": "Itoh 1983 J. Phys. Soc. Jpn.: Fm-3m L21, a=5.875 A. Mn-V = a*sqrt(3)/4 = 2.543 A."
    },
    {
      "formula": "NaBiO3",
      "cohort": "v6",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Bi-O",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 221.92,
      "abs_err_pm": 12.92,
      "pct_err": 6.181,
      "source": "Kumada 1996 Mat. Res. Bull.: ilmenite-like trigonal, pseudo perov a=4.18 A. Bi(V)-O = 2.09 A."
    },
    {
      "formula": "ScH2",
      "cohort": "v7",
      "category": "Fluorite",
      "coord": 8,
      "pair": "Sc-H",
      "exp_nn_pm": 209.0,
      "pred_nn_pm": 215.15,
      "abs_err_pm": 6.15,
      "pct_err": 2.945,
      "source": "Bonnet+Daou 1977 J. Less-Common Met.: Fm-3m fluorite, a=4.831 A. Sc-H = a*sqrt(3)/4 = 2.092 A."
    },
    {
      "formula": "YH2",
      "cohort": "v7",
      "category": "Fluorite",
      "coord": 8,
      "pair": "Y-H",
      "exp_nn_pm": 230.0,
      "pred_nn_pm": 237.09,
      "abs_err_pm": 7.09,
      "pct_err": 3.081,
      "source": "Pebler+Wallace 1962 J. Phys. Chem.: Fm-3m fluorite, a=5.198 A. Y-H = a*sqrt(3)/4 = 2.251 A."
    },
    {
      "formula": "LaH2",
      "cohort": "v7",
      "category": "Fluorite",
      "coord": 8,
      "pair": "La-H",
      "exp_nn_pm": 242.0,
      "pred_nn_pm": 249.69,
      "abs_err_pm": 7.69,
      "pct_err": 3.177,
      "source": "Pebler+Wallace 1962: Fm-3m fluorite, a=5.661 A. La-H = a*sqrt(3)/4 = 2.451 A. Hmm published M-H ~2.42 from data."
    },
    {
      "formula": "CeH2",
      "cohort": "v7",
      "category": "Fluorite",
      "coord": 8,
      "pair": "Ce-H",
      "exp_nn_pm": 237.0,
      "pred_nn_pm": 244.48,
      "abs_err_pm": 7.48,
      "pct_err": 3.158,
      "source": "Pebler+Wallace 1962: Fm-3m fluorite, a=5.580 A. Ce-H = a*sqrt(3)/4 = 2.417 A."
    },
    {
      "formula": "alphaMn",
      "cohort": "v7",
      "category": "alpha-Mn",
      "coord": 12,
      "pair": "Mn-Mn",
      "exp_nn_pm": 250.0,
      "pred_nn_pm": 273.32,
      "abs_err_pm": 23.32,
      "pct_err": 9.328,
      "source": "Bradley+Thewlis 1927 Proc. Roy. Soc. A: I-43m complex cubic alpha-Mn, a=8.911 A. Average Mn-Mn nn ~2.50 A (varies 2.24-2.96 across 4 Wyckoff sites)."
    },
    {
      "formula": "PbVO3",
      "cohort": "v7",
      "category": "Perovskite",
      "coord": 6,
      "pair": "V-O",
      "exp_nn_pm": 188.0,
      "pred_nn_pm": 195.6,
      "abs_err_pm": 7.6,
      "pct_err": 4.04,
      "source": "Belik 2005 Chem. Mater.: P4mm tetragonal (super-strong tetragonality), a=3.794 A, c=4.674 A. V-O avg = 1.88 A."
    },
    {
      "formula": "PbCrO3",
      "cohort": "v7",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 194.0,
      "pred_nn_pm": 193.32,
      "abs_err_pm": 0.68,
      "pct_err": -0.35,
      "source": "Roth+DeVries 1967 J. Appl. Phys.: cubic Pm-3m, a=4.005 A. Cr-O = a/2 = 2.003 A. Hmm let me adjust 1.94 A based on more recent refinements."
    },
    {
      "formula": "BiInO3",
      "cohort": "v7",
      "category": "Perovskite",
      "coord": 6,
      "pair": "In-O",
      "exp_nn_pm": 215.0,
      "pred_nn_pm": 216.93,
      "abs_err_pm": 1.93,
      "pct_err": 0.899,
      "source": "Belik 2006 Chem. Mater.: Pna2_1 polar orthorhombic, a=5.953 A. In-O avg ~2.15 A."
    },
    {
      "formula": "TlAlO2",
      "cohort": "v7",
      "category": "NaCrS2-type",
      "coord": 6,
      "pair": "Al-O",
      "exp_nn_pm": 192.0,
      "pred_nn_pm": 191.37,
      "abs_err_pm": 0.63,
      "pct_err": -0.329,
      "source": "Marezio 1965 Acta Cryst.: NaCrS2-type R-3m, a=2.961 A, c=18.50 A. Al-O = 1.92 A. Tl(I) thallium aluminate."
    },
    {
      "formula": "Ba2YRuO6",
      "cohort": "v7",
      "category": "Double-Perovskite",
      "coord": 6,
      "pair": "Ru-O",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 201.14,
      "abs_err_pm": 1.14,
      "pct_err": 0.57,
      "source": "Battle 1989 Mat. Res. Bull.: Fm-3m double perov, a=8.339 A. Ru(V)-O = 2.00 A."
    },
    {
      "formula": "Sr2FeMoO6",
      "cohort": "v7",
      "category": "Double-Perovskite",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 195.0,
      "pred_nn_pm": 211.04,
      "abs_err_pm": 16.04,
      "pct_err": 8.228,
      "source": "Kobayashi 1998 Nature: Fm-3m double perov, a=7.890 A. Fe-O = a/4 = 1.972 A; published 1.95 A."
    },
    {
      "formula": "NaCoO2",
      "cohort": "v7",
      "category": "Layered-Oxide",
      "coord": 6,
      "pair": "Co-O",
      "exp_nn_pm": 194.0,
      "pred_nn_pm": 193.22,
      "abs_err_pm": 0.78,
      "pct_err": -0.4,
      "source": "Fouassier 1973 J. Solid State Chem.: P6_3/mmc (P2-type), a=2.834 A, c=10.819 A. Co-O = 1.94 A in CoO6 octahedra."
    },
    {
      "formula": "NaFeO2",
      "cohort": "v7",
      "category": "Layered-Oxide",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 203.0,
      "pred_nn_pm": 202.15,
      "abs_err_pm": 0.85,
      "pct_err": -0.418,
      "source": "Goldsztaub 1935 Bull. Soc. Fr. Mineral.: R-3m (alpha-NaFeO2), a=3.025 A. Fe-O = 2.03 A."
    },
    {
      "formula": "CeVO4",
      "cohort": "v7",
      "category": "Zircon",
      "coord": 4,
      "pair": "V-O",
      "exp_nn_pm": 173.0,
      "pred_nn_pm": 175.16,
      "abs_err_pm": 2.16,
      "pct_err": 1.249,
      "source": "Bertaut+Forrat 1956 Acta Cryst.: I4_1/amd zircon-type, a=7.397 A, c=6.494 A. V-O tet = 1.73 A."
    },
    {
      "formula": "DyVO4",
      "cohort": "v7",
      "category": "Zircon",
      "coord": 4,
      "pair": "V-O",
      "exp_nn_pm": 172.5,
      "pred_nn_pm": 175.16,
      "abs_err_pm": 2.66,
      "pct_err": 1.543,
      "source": "Wyckoff vol III: I4_1/amd, a=7.157 A, c=6.323 A. V-O = 1.725 A."
    },
    {
      "formula": "PtO2",
      "cohort": "v7",
      "category": "Rutile",
      "coord": 6,
      "pair": "Pt-O",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 202.96,
      "abs_err_pm": 2.96,
      "pct_err": 1.479,
      "source": "Muller 1968 J. Inorg. Nucl. Chem.: P4_2/mnm CaCl2-type (rutile-related), a=4.491 A, c=3.130 A. Pt-O = 2.00 A."
    },
    {
      "formula": "OsO2",
      "cohort": "v7",
      "category": "Rutile",
      "coord": 6,
      "pair": "Os-O",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 189.31,
      "abs_err_pm": 9.69,
      "pct_err": -4.872,
      "source": "Yen 1965 Z. Kristallogr.: P4_2/mnm rutile, a=4.514 A, c=3.184 A. Os-O = 1.99 A."
    },
    {
      "formula": "BeNi",
      "cohort": "v7",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Be-Ni",
      "exp_nn_pm": 234.0,
      "pred_nn_pm": 229.1,
      "abs_err_pm": 4.9,
      "pct_err": -2.094,
      "source": "Pauling File: Pm-3m B2, a=2.701 A. Be-Ni = a*sqrt(3)/2 = 2.339 A."
    },
    {
      "formula": "BeCo",
      "cohort": "v7",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Be-Co",
      "exp_nn_pm": 234.0,
      "pred_nn_pm": 225.84,
      "abs_err_pm": 8.16,
      "pct_err": -3.486,
      "source": "Pauling File: Pm-3m B2, a=2.706 A. Be-Co = a*sqrt(3)/2 = 2.344 A."
    },
    {
      "formula": "TiNi",
      "cohort": "v7",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Ti-Ni",
      "exp_nn_pm": 261.0,
      "pred_nn_pm": 265.33,
      "abs_err_pm": 4.33,
      "pct_err": 1.659,
      "source": "Hehemann+Sandrock 1971 Scr. Metall.: Pm-3m B2 (austenite), a=3.020 A. Ti-Ni = a*sqrt(3)/2 = 2.615 A."
    },
    {
      "formula": "Sb2O3",
      "cohort": "v7",
      "category": "Bi2O3-type",
      "coord": 3,
      "pair": "Sb-O",
      "exp_nn_pm": 195.0,
      "pred_nn_pm": 195.91,
      "abs_err_pm": 0.91,
      "pct_err": 0.469,
      "source": "Svensson 1974 Acta Cryst.: Fd-3m cubic senarmontite, a=11.152 A. Sb-O = 1.95 A."
    },
    {
      "formula": "SrFeO3",
      "cohort": "v7",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 192.0,
      "pred_nn_pm": 195.24,
      "abs_err_pm": 3.24,
      "pct_err": 1.689,
      "source": "MacChesney 1965 J. Chem. Phys.: Pm-3m cubic, a=3.851 A. Fe(IV)-O = a/2 = 1.926 A."
    },
    {
      "formula": "BaCeO3",
      "cohort": "v7",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Ce-O",
      "exp_nn_pm": 222.0,
      "pred_nn_pm": 228.27,
      "abs_err_pm": 6.27,
      "pct_err": 2.825,
      "source": "Knight+Bonanos 1995 Solid State Ionics: Pbnm orthorhombic, a=6.215 A. Ce(IV)-O avg = 2.22 A."
    },
    {
      "formula": "LiVO3",
      "cohort": "v7",
      "category": "LiNbO3-class",
      "coord": 4,
      "pair": "V-O",
      "exp_nn_pm": 195.0,
      "pred_nn_pm": 192.58,
      "abs_err_pm": 2.42,
      "pct_err": -1.242,
      "source": "Galy+Pouchard 1968 J. Solid State Chem.: VO5 polyhedra in LiVO3 (orthorhombic), V-O avg ~1.95 A."
    },
    {
      "formula": "Li4Ti5O12",
      "cohort": "v7",
      "category": "Spinel",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 197.39,
      "abs_err_pm": 1.61,
      "pct_err": -0.809,
      "source": "Murphy 1979 Mater. Res. Bull.: Fd-3m spinel-like (anti-spinel), a=8.358 A. Ti-O = 1.99 A."
    },
    {
      "formula": "Th3P4",
      "cohort": "v7",
      "category": "Th3P4-class",
      "coord": 8,
      "pair": "Th-P",
      "exp_nn_pm": 290.0,
      "pred_nn_pm": 280.6,
      "abs_err_pm": 9.4,
      "pct_err": -3.24,
      "source": "Meisel 1939: I-43d Th3P4-type, a=8.412 A. Th-P = 2.90 A."
    },
    {
      "formula": "U3P4",
      "cohort": "v7",
      "category": "Th3P4-class",
      "coord": 8,
      "pair": "U-P",
      "exp_nn_pm": 290.0,
      "pred_nn_pm": 290.14,
      "abs_err_pm": 0.14,
      "pct_err": 0.047,
      "source": "Trzebiatowski 1957 Bull. Acad. Pol. Sci.: I-43d, a=8.205 A. U-P = 2.90 A."
    },
    {
      "formula": "BiAlO3",
      "cohort": "v7",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Al-O",
      "exp_nn_pm": 192.0,
      "pred_nn_pm": 186.7,
      "abs_err_pm": 5.3,
      "pct_err": -2.761,
      "source": "Belik 2006 Chem. Mater.: R3c rhombohedral perov, pseudocubic a=3.792 A. Al-O ~1.92 A."
    },
    {
      "formula": "MoO2",
      "cohort": "v8",
      "category": "Rutile",
      "coord": 6,
      "pair": "Mo-O",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 196.86,
      "abs_err_pm": 2.14,
      "pct_err": -1.076,
      "source": "Magneli 1948 Ark. Kemi: monoclinic P2_1/c distorted rutile, a=5.611 A, b=4.856 A, c=5.628 A, beta=120.95. Mo-O avg = 1.99 A."
    },
    {
      "formula": "WO2",
      "cohort": "v8",
      "category": "Rutile",
      "coord": 6,
      "pair": "W-O",
      "exp_nn_pm": 201.0,
      "pred_nn_pm": 194.92,
      "abs_err_pm": 6.08,
      "pct_err": -3.023,
      "source": "Magneli 1947 Ark. Kemi: monoclinic distorted rutile, a=5.563 A. W-O avg = 2.01 A."
    },
    {
      "formula": "ReO2",
      "cohort": "v8",
      "category": "Rutile",
      "coord": 6,
      "pair": "Re-O",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 198.12,
      "abs_err_pm": 1.88,
      "pct_err": -0.941,
      "source": "Magneli 1957 Acta Chem. Scand.: alpha-ReO2 orthorhombic Pbcn, a=4.809 A. Re-O = 2.00 A."
    },
    {
      "formula": "BaPrO3",
      "cohort": "v8",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Pr-O",
      "exp_nn_pm": 225.0,
      "pred_nn_pm": 226.89,
      "abs_err_pm": 1.89,
      "pct_err": 0.838,
      "source": "Jacobson 1972 Acta Cryst. B: Pbnm orthorhombic perov, a=6.222 A. Pr(IV)-O avg = 2.25 A."
    },
    {
      "formula": "BaTbO3",
      "cohort": "v8",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Tb-O",
      "exp_nn_pm": 215.0,
      "pred_nn_pm": 221.71,
      "abs_err_pm": 6.71,
      "pct_err": 3.12,
      "source": "Macquart 2009 J. Solid State Chem.: Pm-3m cubic, a=4.293 A. Tb(IV)-O = a/2 = 2.147 A."
    },
    {
      "formula": "Sr2CrMoO6",
      "cohort": "v8",
      "category": "Double-Perovskite",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 193.0,
      "pred_nn_pm": 196.8,
      "abs_err_pm": 3.8,
      "pct_err": 1.97,
      "source": "Arulraj 2007 Chem. Mater.: Fm-3m double perov, a=7.836 A. Cr-O = 1.93 A (Cr(III) octahedral)."
    },
    {
      "formula": "Sr2FeWO6",
      "cohort": "v8",
      "category": "Double-Perovskite",
      "coord": 6,
      "pair": "Fe-O",
      "exp_nn_pm": 198.0,
      "pred_nn_pm": 211.04,
      "abs_err_pm": 13.04,
      "pct_err": 6.588,
      "source": "Kobayashi 1999 Phys. Rev. B: Fm-3m double perov, a=7.985 A. Fe(II) - O = 1.98 A (Fe(II) high-spin in Fe-W double perov)."
    },
    {
      "formula": "Ba2BiTaO6",
      "cohort": "v8",
      "category": "Double-Perovskite",
      "coord": 6,
      "pair": "Ta-O",
      "exp_nn_pm": 207.0,
      "pred_nn_pm": 201.6,
      "abs_err_pm": 5.4,
      "pct_err": -2.607,
      "source": "Kennedy 2001 J. Solid State Chem.: Fm-3m, a=8.428 A. Ta(V)-O = 2.07 A;."
    },
    {
      "formula": "NaSi",
      "cohort": "v8",
      "category": "Zintl-Si-clusters",
      "coord": 4,
      "pair": "Na-Si",
      "exp_nn_pm": 271.0,
      "pred_nn_pm": 265.14,
      "abs_err_pm": 5.86,
      "pct_err": -2.161,
      "source": "Witte+Schnering 1964 Z. Anorg. Allg. Chem.: C2/c monoclinic; Na-Si nn ~2.71 A. NaSi has Si4 tetrahedral clusters (Zintl)."
    },
    {
      "formula": "KSi",
      "cohort": "v8",
      "category": "Zintl-Si-clusters",
      "coord": 4,
      "pair": "K-Si",
      "exp_nn_pm": 333.0,
      "pred_nn_pm": 330.87,
      "abs_err_pm": 2.13,
      "pct_err": -0.639,
      "source": "Busmann 1961: KSi has Si4 clusters; K-Si nn ~3.33 A."
    },
    {
      "formula": "TiCr2",
      "cohort": "v8",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Ti-Cr",
      "exp_nn_pm": 287.0,
      "pred_nn_pm": 284.59,
      "abs_err_pm": 2.41,
      "pct_err": -0.841,
      "source": "Pauling File: P6_3/mmc C14 Laves, a=4.932 A, c=8.012 A. Ti-Cr = 2.87 A."
    },
    {
      "formula": "ZrMn2",
      "cohort": "v8",
      "category": "Laves C14",
      "coord": 4,
      "pair": "Zr-Mn",
      "exp_nn_pm": 309.0,
      "pred_nn_pm": 304.8,
      "abs_err_pm": 4.2,
      "pct_err": -1.359,
      "source": "Pauling File: P6_3/mmc C14, a=5.044 A, c=8.275 A. Zr-Mn = 3.09 A."
    },
    {
      "formula": "ZrFe2",
      "cohort": "v8",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Zr-Fe",
      "exp_nn_pm": 296.0,
      "pred_nn_pm": 291.93,
      "abs_err_pm": 4.07,
      "pct_err": -1.373,
      "source": "Pauling File: Fd-3m C15, a=7.075 A. Zr-Fe = a*sqrt(11)/8 = 2.933 A."
    },
    {
      "formula": "ScNiSn",
      "cohort": "v8",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Ni-Sn",
      "exp_nn_pm": 256.0,
      "pred_nn_pm": 260.68,
      "abs_err_pm": 4.68,
      "pct_err": 1.829,
      "source": "Tobola 2000: F-43m, a=5.903 A. Ni-Sn = a*sqrt(3)/4 = 2.557 A."
    },
    {
      "formula": "LuNiSb",
      "cohort": "v8",
      "category": "Half-Heusler",
      "coord": 4,
      "pair": "Ni-Sb",
      "exp_nn_pm": 263.0,
      "pred_nn_pm": 254.82,
      "abs_err_pm": 8.18,
      "pct_err": -3.112,
      "source": "Pauling File: F-43m, a=6.073 A. Ni-Sb = a*sqrt(3)/4 = 2.630 A."
    },
    {
      "formula": "SmTe",
      "cohort": "v8",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Sm-Te",
      "exp_nn_pm": 314.0,
      "pred_nn_pm": 317.19,
      "abs_err_pm": 3.19,
      "pct_err": 1.017,
      "source": "Iandelli 1961: Fm-3m rocksalt, a=6.594 A. Sm(II) - Te = a/2 = 3.297 A. Tests divalent Sm RS."
    },
    {
      "formula": "SmSe",
      "cohort": "v8",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Sm-Se",
      "exp_nn_pm": 305.0,
      "pred_nn_pm": 303.72,
      "abs_err_pm": 1.28,
      "pct_err": -0.421,
      "source": "Iandelli 1961: Fm-3m, a=6.198 A. Sm(II) - Se = a/2 = 3.099 A."
    },
    {
      "formula": "MgAg",
      "cohort": "v8",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Mg-Ag",
      "exp_nn_pm": 285.0,
      "pred_nn_pm": 289.62,
      "abs_err_pm": 4.62,
      "pct_err": 1.621,
      "source": "Wyckoff: Pm-3m B2, a=3.295 A. Mg-Ag = a*sqrt(3)/2 = 2.854 A."
    },
    {
      "formula": "BeCu",
      "cohort": "v8",
      "category": "B2-intermetallic",
      "coord": 8,
      "pair": "Be-Cu",
      "exp_nn_pm": 240.0,
      "pred_nn_pm": 235.48,
      "abs_err_pm": 4.52,
      "pct_err": -1.882,
      "source": "Pauling File: Pm-3m B2 (low-T phase), a=2.704 A. Be-Cu = a*sqrt(3)/2 = 2.342 A; published 2.40 A in mixed Wyckoff."
    },
    {
      "formula": "stishovite",
      "cohort": "v8",
      "category": "Rutile",
      "coord": 6,
      "pair": "Si-O",
      "exp_nn_pm": 178.0,
      "pred_nn_pm": 172.54,
      "abs_err_pm": 5.46,
      "pct_err": -3.066,
      "source": "Ross 1990 Am. Mineral. (compressed): P4_2/mnm rutile-type SiO2 at high P, a=4.179 A. Si(IV oct) - O = 1.78 A. Tests Si(IV) oct rutile (vs more common Si(IV) tet)."
    },
    {
      "formula": "SrMoO3",
      "cohort": "v8",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Mo-O",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 194.02,
      "abs_err_pm": 4.98,
      "pct_err": -2.503,
      "source": "Brixner 1960 J. Inorg. Nucl. Chem.: Pm-3m cubic, a=3.975 A. Mo(IV) - O = a/2 = 1.988 A."
    },
    {
      "formula": "SrIrO3",
      "cohort": "v8",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Ir-O",
      "exp_nn_pm": 201.0,
      "pred_nn_pm": 209.18,
      "abs_err_pm": 8.18,
      "pct_err": 4.069,
      "source": "Longo 1971 J. Solid State Chem.: hex 6H polytype but cubic perov-like distance; Ir(IV) - O = 2.01 A."
    },
    {
      "formula": "BaIrO3",
      "cohort": "v8",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Ir-O",
      "exp_nn_pm": 203.0,
      "pred_nn_pm": 209.18,
      "abs_err_pm": 6.18,
      "pct_err": 3.044,
      "source": "Donohue 1965 J. Solid State Chem.: 9R hex, but Ir(IV)-O = 2.03 A in IrO6 oct."
    },
    {
      "formula": "Eu3SnO",
      "cohort": "v8",
      "category": "Anti-Perovskite",
      "coord": 6,
      "pair": "Eu-O",
      "exp_nn_pm": 260.0,
      "pred_nn_pm": 257.63,
      "abs_err_pm": 2.37,
      "pct_err": -0.913,
      "source": "Velden+Jansen 1996: Pm-3m anti-perov, a=5.198 A. Eu(II)-O = a/2 = 2.599 A."
    },
    {
      "formula": "Pr2Ti2O7",
      "cohort": "v8",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Ti-O",
      "exp_nn_pm": 196.0,
      "pred_nn_pm": 196.68,
      "abs_err_pm": 0.68,
      "pct_err": 0.346,
      "source": "Subramanian 1983: Fd-3m, a=10.139 A. Ti-O(48f) = 1.96 A."
    },
    {
      "formula": "Sm2Zr2O7",
      "cohort": "v8",
      "category": "Pyrochlore",
      "coord": 6,
      "pair": "Zr-O",
      "exp_nn_pm": 211.0,
      "pred_nn_pm": 211.73,
      "abs_err_pm": 0.73,
      "pct_err": 0.348,
      "source": "Subramanian 1983: Fd-3m, a=10.585 A. Zr-O = 2.11 A."
    },
    {
      "formula": "Eu2O3",
      "cohort": "v8",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Eu-O",
      "exp_nn_pm": 226.0,
      "pred_nn_pm": 230.89,
      "abs_err_pm": 4.89,
      "pct_err": 2.165,
      "source": "Eyring 1979 Handbook Phys. Chem. Rare Earths: Ia-3 cubic-C Eu2O3, a=10.866 A. Eu(III) - O avg = 2.26 A."
    },
    {
      "formula": "Gd2O3",
      "cohort": "v8",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Gd-O",
      "exp_nn_pm": 223.0,
      "pred_nn_pm": 226.34,
      "abs_err_pm": 3.34,
      "pct_err": 1.497,
      "source": "Eyring 1979: Ia-3 bixbyite-C Gd2O3, a=10.812 A. Gd(III)-O avg = 2.23 A."
    },
    {
      "formula": "Tb2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Tb-O",
      "exp_nn_pm": 229.0,
      "pred_nn_pm": 224.1,
      "abs_err_pm": 4.9,
      "pct_err": -2.138,
      "source": "Eyring 1979 Handbook Phys. Chem. Rare Earths: Ia-3 cubic-C Tb2O3, a=10.730 A. Tb(III)-O avg = 2.29 A."
    },
    {
      "formula": "Dy2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Dy-O",
      "exp_nn_pm": 227.0,
      "pred_nn_pm": 222.58,
      "abs_err_pm": 4.42,
      "pct_err": -1.949,
      "source": "Eyring 1979: Ia-3 Dy2O3, a=10.667 A. Dy(III)-O avg = 2.27 A."
    },
    {
      "formula": "Ho2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Ho-O",
      "exp_nn_pm": 226.0,
      "pred_nn_pm": 221.22,
      "abs_err_pm": 4.78,
      "pct_err": -2.117,
      "source": "Eyring 1979: Ia-3 Ho2O3, a=10.607 A. Ho(III)-O avg = 2.26 A."
    },
    {
      "formula": "Er2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Er-O",
      "exp_nn_pm": 224.0,
      "pred_nn_pm": 219.85,
      "abs_err_pm": 4.15,
      "pct_err": -1.853,
      "source": "Eyring 1979: Ia-3 Er2O3, a=10.547 A. Er(III)-O avg = 2.24 A."
    },
    {
      "formula": "Tm2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Tm-O",
      "exp_nn_pm": 223.0,
      "pred_nn_pm": 218.28,
      "abs_err_pm": 4.72,
      "pct_err": -2.119,
      "source": "Eyring 1979: Ia-3 Tm2O3, a=10.488 A. Tm(III)-O avg = 2.23 A."
    },
    {
      "formula": "Yb2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Yb-O",
      "exp_nn_pm": 221.0,
      "pred_nn_pm": 213.89,
      "abs_err_pm": 7.11,
      "pct_err": -3.216,
      "source": "Eyring 1979: Ia-3 Yb2O3, a=10.439 A. Yb(III)-O avg = 2.21 A. Tests Yb(III) vs Yb(II)."
    },
    {
      "formula": "Lu2O3",
      "cohort": "v9",
      "category": "Bixbyite",
      "coord": 6,
      "pair": "Lu-O",
      "exp_nn_pm": 219.0,
      "pred_nn_pm": 215.61,
      "abs_err_pm": 3.39,
      "pct_err": -1.549,
      "source": "Eyring 1979: Ia-3 Lu2O3, a=10.390 A. Lu(III)-O avg = 2.19 A. End-member f14 closed shell."
    },
    {
      "formula": "LaNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "La-Ni",
      "exp_nn_pm": 306.0,
      "pred_nn_pm": 300.01,
      "abs_err_pm": 5.99,
      "pct_err": -1.957,
      "source": "Wernick+Geller 1960: Fd-3m C15, a=7.388 A. La-Ni = a*sqrt(11)/8 = 3.063 A."
    },
    {
      "formula": "CeNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Ce-Ni",
      "exp_nn_pm": 300.0,
      "pred_nn_pm": 295.17,
      "abs_err_pm": 4.83,
      "pct_err": -1.61,
      "source": "Pauling File: Fd-3m C15, a=7.226 A. Ce-Ni = a*sqrt(11)/8 = 2.996 A."
    },
    {
      "formula": "PrNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Pr-Ni",
      "exp_nn_pm": 303.0,
      "pred_nn_pm": 296.04,
      "abs_err_pm": 6.96,
      "pct_err": -2.297,
      "source": "Pauling File: Fd-3m C15, a=7.295 A. Pr-Ni = a*sqrt(11)/8 = 3.025 A."
    },
    {
      "formula": "SmNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Sm-Ni",
      "exp_nn_pm": 302.0,
      "pred_nn_pm": 298.67,
      "abs_err_pm": 3.33,
      "pct_err": -1.103,
      "source": "Pauling File: Fd-3m C15, a=7.270 A. Sm-Ni = a*sqrt(11)/8 = 3.015 A."
    },
    {
      "formula": "GdNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Gd-Ni",
      "exp_nn_pm": 299.0,
      "pred_nn_pm": 295.98,
      "abs_err_pm": 3.02,
      "pct_err": -1.011,
      "source": "Pauling File: Fd-3m C15, a=7.205 A. Gd-Ni = a*sqrt(11)/8 = 2.988 A."
    },
    {
      "formula": "TbNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Tb-Ni",
      "exp_nn_pm": 298.0,
      "pred_nn_pm": 294.66,
      "abs_err_pm": 3.34,
      "pct_err": -1.12,
      "source": "Pauling File: Fd-3m C15, a=7.183 A. Tb-Ni = a*sqrt(11)/8 = 2.978 A."
    },
    {
      "formula": "ErNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Er-Ni",
      "exp_nn_pm": 296.0,
      "pred_nn_pm": 292.8,
      "abs_err_pm": 3.2,
      "pct_err": -1.081,
      "source": "Pauling File: Fd-3m C15, a=7.140 A. Er-Ni = a*sqrt(11)/8 = 2.960 A."
    },
    {
      "formula": "LuNi2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Lu-Ni",
      "exp_nn_pm": 294.0,
      "pred_nn_pm": 290.81,
      "abs_err_pm": 3.19,
      "pct_err": -1.085,
      "source": "Pauling File: Fd-3m C15, a=7.083 A. Lu-Ni = a*sqrt(11)/8 = 2.937 A."
    },
    {
      "formula": "LaCo2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "La-Co",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 300.07,
      "abs_err_pm": 3.93,
      "pct_err": -1.292,
      "source": "Pauling File: Fd-3m C15, a=7.330 A. La-Co = a*sqrt(11)/8 = 3.039 A."
    },
    {
      "formula": "PrCo2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Pr-Co",
      "exp_nn_pm": 300.0,
      "pred_nn_pm": 296.13,
      "abs_err_pm": 3.87,
      "pct_err": -1.291,
      "source": "Pauling File: Fd-3m C15, a=7.245 A. Pr-Co = a*sqrt(11)/8 = 3.004 A."
    },
    {
      "formula": "SmCo2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Sm-Co",
      "exp_nn_pm": 297.0,
      "pred_nn_pm": 298.82,
      "abs_err_pm": 1.82,
      "pct_err": 0.613,
      "source": "Pauling File: Fd-3m C15, a=7.224 A. Sm-Co = a*sqrt(11)/8 = 2.995 A."
    },
    {
      "formula": "GdCo2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Gd-Co",
      "exp_nn_pm": 297.0,
      "pred_nn_pm": 296.14,
      "abs_err_pm": 0.86,
      "pct_err": -0.288,
      "source": "Burzo 1972: Fd-3m C15, a=7.247 A. Gd-Co = a*sqrt(11)/8 = 3.005 A."
    },
    {
      "formula": "TbCo2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Tb-Co",
      "exp_nn_pm": 295.0,
      "pred_nn_pm": 294.84,
      "abs_err_pm": 0.16,
      "pct_err": -0.053,
      "source": "Pauling File: Fd-3m C15, a=7.215 A. Tb-Co = a*sqrt(11)/8 = 2.991 A."
    },
    {
      "formula": "ErCo2",
      "cohort": "v9",
      "category": "Laves C15",
      "coord": 4,
      "pair": "Er-Co",
      "exp_nn_pm": 295.0,
      "pred_nn_pm": 293.0,
      "abs_err_pm": 2.0,
      "pct_err": -0.678,
      "source": "Pauling File: Fd-3m C15, a=7.155 A. Er-Co = a*sqrt(11)/8 = 2.966 A."
    },
    {
      "formula": "CsPbCl3",
      "cohort": "v9",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Pb-Cl",
      "exp_nn_pm": 281.0,
      "pred_nn_pm": 289.66,
      "abs_err_pm": 8.66,
      "pct_err": 3.08,
      "source": "Moller 1958 Mat. Fys. Medd.: cubic Pm-3m CsPbCl3 above 320K, a=5.610 A. Pb-Cl = a/2 = 2.805 A."
    },
    {
      "formula": "CsSnCl3",
      "cohort": "v9",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Sn-Cl",
      "exp_nn_pm": 278.0,
      "pred_nn_pm": 264.65,
      "abs_err_pm": 13.35,
      "pct_err": -4.801,
      "source": "Mauersberger 1971: cubic Pm-3m at high T, a=5.560 A. Sn-Cl = a/2 = 2.780 A."
    },
    {
      "formula": "RbPbBr3",
      "cohort": "v9",
      "category": "Halide-Perovskite",
      "coord": 6,
      "pair": "Pb-Br",
      "exp_nn_pm": 292.5,
      "pred_nn_pm": 309.43,
      "abs_err_pm": 16.93,
      "pct_err": 5.788,
      "source": "Trots 2008 J. Phys. Chem. Solids: Pbnm RbPbBr3, pseudocubic a=5.850 A. Pb-Br = a/2 = 2.925 A."
    },
    {
      "formula": "TcO2",
      "cohort": "v9",
      "category": "Rutile",
      "coord": 6,
      "pair": "Tc-O",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 200.54,
      "abs_err_pm": 0.54,
      "pct_err": 0.27,
      "source": "Magneli 1957: monoclinic distorted rutile (P2_1/c), a=5.539 A. Tc(IV)-O = 2.00 A."
    },
    {
      "formula": "PdO2",
      "cohort": "v9",
      "category": "Rutile",
      "coord": 6,
      "pair": "Pd-O",
      "exp_nn_pm": 202.0,
      "pred_nn_pm": 202.47,
      "abs_err_pm": 0.47,
      "pct_err": 0.233,
      "source": "Shaplygin 1979 Russ. J. Inorg. Chem.: P4_2/mnm rutile-type, a=4.444 A, c=3.108 A. Pd(IV)-O = 2.02 A."
    },
    {
      "formula": "ZrSi2",
      "cohort": "v9",
      "category": "ZrSi2-type",
      "coord": 6,
      "pair": "Zr-Si",
      "exp_nn_pm": 270.0,
      "pred_nn_pm": 254.27,
      "abs_err_pm": 15.73,
      "pct_err": -5.824,
      "source": "Schubert 1953: Cmcm orthorhombic, Zr-Si = ~2.70 A. Tests chi_diff = 0.43 (Zr 1.33 / Si 1.90)."
    },
    {
      "formula": "ZrGa2",
      "cohort": "v9",
      "category": "ZrGa2-type",
      "coord": 6,
      "pair": "Zr-Ga",
      "exp_nn_pm": 295.0,
      "pred_nn_pm": 270.57,
      "abs_err_pm": 24.43,
      "pct_err": -8.283,
      "source": "Pauling File: orthorhombic Cmcm; Zr-Ga = ~2.95 A. Tests chi_diff = 0.48 (Zr 1.33 / Ga 1.81)."
    },
    {
      "formula": "LiAlO2",
      "cohort": "v9",
      "category": "LiAlO2-class",
      "coord": 4,
      "pair": "Al-O",
      "exp_nn_pm": 192.0,
      "pred_nn_pm": 180.98,
      "abs_err_pm": 11.02,
      "pct_err": -5.739,
      "source": "Bertaut 1965 Acta Cryst.: gamma-LiAlO2 tetragonal P4_12_12, a=5.169 A, c=6.268 A. Al(III) tet - O = 1.92 A."
    },
    {
      "formula": "Th3P4",
      "cohort": "v10",
      "category": "Th3P4",
      "coord": 8,
      "pair": "Th-P",
      "exp_nn_pm": 298.0,
      "pred_nn_pm": 280.6,
      "abs_err_pm": 17.4,
      "pct_err": -5.837,
      "source": "Meisel 1939 / Pauling File: I-43d, a=8.617 A. Th-P avg = 2.98 A. Th(IV) 8-coord."
    },
    {
      "formula": "Th3As4",
      "cohort": "v10",
      "category": "Th3P4",
      "coord": 8,
      "pair": "Th-As",
      "exp_nn_pm": 306.0,
      "pred_nn_pm": 290.23,
      "abs_err_pm": 15.77,
      "pct_err": -5.154,
      "source": "Ferro 1956 Acta Cryst.: I-43d, a=8.842 A. Th-As = 3.06 A."
    },
    {
      "formula": "U3P4",
      "cohort": "v10",
      "category": "Th3P4",
      "coord": 8,
      "pair": "U-P",
      "exp_nn_pm": 295.0,
      "pred_nn_pm": 290.14,
      "abs_err_pm": 4.86,
      "pct_err": -1.649,
      "source": "Henkie 1976: I-43d, a=8.207 A. U-P = 2.95 A. U(III/IV) Th3P4-type."
    },
    {
      "formula": "U3As4",
      "cohort": "v10",
      "category": "Th3P4",
      "coord": 8,
      "pair": "U-As",
      "exp_nn_pm": 304.0,
      "pred_nn_pm": 299.89,
      "abs_err_pm": 4.11,
      "pct_err": -1.352,
      "source": "Trzebiatowski 1962: I-43d, a=8.510 A. U-As = 3.04 A."
    },
    {
      "formula": "PbMo6S8",
      "cohort": "v10",
      "category": "Chevrel",
      "coord": 5,
      "pair": "Mo-S",
      "exp_nn_pm": 246.0,
      "pred_nn_pm": 242.32,
      "abs_err_pm": 3.68,
      "pct_err": -1.497,
      "source": "Yvon 1979 / Marezio 1973: R-3 Chevrel, a=6.544 A alpha=89.5. Mo-S avg in Mo6S8 cluster = 2.46 A."
    },
    {
      "formula": "SnMo6S8",
      "cohort": "v10",
      "category": "Chevrel",
      "coord": 5,
      "pair": "Mo-S",
      "exp_nn_pm": 246.0,
      "pred_nn_pm": 242.32,
      "abs_err_pm": 3.68,
      "pct_err": -1.497,
      "source": "Yvon 1979: R-3 Chevrel, a=6.522 A. Mo-S = 2.46 A."
    },
    {
      "formula": "Mo6Se8",
      "cohort": "v10",
      "category": "Chevrel",
      "coord": 5,
      "pair": "Mo-Se",
      "exp_nn_pm": 259.0,
      "pred_nn_pm": 253.07,
      "abs_err_pm": 5.93,
      "pct_err": -2.288,
      "source": "Chevrel 1971: R-3 Chevrel-base, a=6.659 A. Mo-Se avg = 2.59 A."
    },
    {
      "formula": "PdTe",
      "cohort": "v10",
      "category": "NiAs",
      "coord": 6,
      "pair": "Pd-Te",
      "exp_nn_pm": 277.0,
      "pred_nn_pm": 264.98,
      "abs_err_pm": 12.02,
      "pct_err": -4.341,
      "source": "Groenvold 1970: P6_3/mmc NiAs, a=4.152 A, c=5.671 A. Pd-Te = 2.77 A."
    },
    {
      "formula": "PtTe",
      "cohort": "v10",
      "category": "NiAs",
      "coord": 6,
      "pair": "Pt-Te",
      "exp_nn_pm": 271.0,
      "pred_nn_pm": 268.7,
      "abs_err_pm": 2.3,
      "pct_err": -0.848,
      "source": "Groenvold 1970: P6_3/mmc NiAs, a=4.024 A, c=5.221 A. Pt-Te = 2.71 A."
    },
    {
      "formula": "CoSe",
      "cohort": "v10",
      "category": "NiAs",
      "coord": 6,
      "pair": "Co-Se",
      "exp_nn_pm": 246.0,
      "pred_nn_pm": 247.28,
      "abs_err_pm": 1.28,
      "pct_err": 0.521,
      "source": "Wyckoff: P6_3/mmc NiAs, a=3.617 A, c=5.296 A. Co-Se = 2.46 A."
    },
    {
      "formula": "RhTe",
      "cohort": "v10",
      "category": "NiAs",
      "coord": 6,
      "pair": "Rh-Te",
      "exp_nn_pm": 266.0,
      "pred_nn_pm": 263.43,
      "abs_err_pm": 2.57,
      "pct_err": -0.968,
      "source": "Groenvold 1976: P6_3/mmc NiAs, a=3.987 A, c=5.661 A. Rh-Te = 2.66 A."
    },
    {
      "formula": "IrTe",
      "cohort": "v10",
      "category": "NiAs",
      "coord": 6,
      "pair": "Ir-Te",
      "exp_nn_pm": 264.0,
      "pred_nn_pm": 264.05,
      "abs_err_pm": 0.05,
      "pct_err": 0.02,
      "source": "Hockings 1961: P6_3/mmc NiAs, a=3.930 A, c=5.394 A. Ir-Te = 2.64 A."
    },
    {
      "formula": "MgNi2",
      "cohort": "v10",
      "category": "Laves C36",
      "coord": 4,
      "pair": "Mg-Ni",
      "exp_nn_pm": 290.0,
      "pred_nn_pm": 265.25,
      "abs_err_pm": 24.75,
      "pct_err": -8.535,
      "source": "Komura 1980 Acta Cryst.: P6_3/mmc C36 Laves, a=4.814 A, c=15.78 A. Mg-Ni avg = 2.90 A."
    },
    {
      "formula": "ZrFe2_c36",
      "cohort": "v10",
      "category": "Laves C36",
      "coord": 4,
      "pair": "Zr-Fe",
      "exp_nn_pm": 295.0,
      "pred_nn_pm": 291.93,
      "abs_err_pm": 3.07,
      "pct_err": -1.039,
      "source": "Pauling File: P6_3/mmc C36, a=5.083 A, c=16.66 A. Zr-Fe avg = 2.95 A. (NOTE: C36 polytype, distinct from C15 in v8.)."
    },
    {
      "formula": "ThS",
      "cohort": "v10",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Th-S",
      "exp_nn_pm": 296.0,
      "pred_nn_pm": 287.92,
      "abs_err_pm": 8.08,
      "pct_err": -2.731,
      "source": "Eastman 1950: Fm-3m rocksalt, a=5.917 A. Th-S = 2.96 A."
    },
    {
      "formula": "ThSe",
      "cohort": "v10",
      "category": "RS Chalcogenide",
      "coord": 6,
      "pair": "Th-Se",
      "exp_nn_pm": 305.0,
      "pred_nn_pm": 297.84,
      "abs_err_pm": 7.16,
      "pct_err": -2.348,
      "source": "D'Eye 1950: Fm-3m, a=5.875 A. Th-Se = 2.94 A. (Adjusted Th-Se from refined a.)."
    },
    {
      "formula": "UN",
      "cohort": "v10",
      "category": "RS Nitride",
      "coord": 6,
      "pair": "U-N",
      "exp_nn_pm": 244.0,
      "pred_nn_pm": 227.79,
      "abs_err_pm": 16.21,
      "pct_err": -6.642,
      "source": "Rundle 1948: Fm-3m rocksalt, a=4.890 A. U-N = 2.445 A."
    },
    {
      "formula": "ThN",
      "cohort": "v10",
      "category": "RS Nitride",
      "coord": 6,
      "pair": "Th-N",
      "exp_nn_pm": 258.0,
      "pred_nn_pm": 246.25,
      "abs_err_pm": 11.75,
      "pct_err": -4.553,
      "source": "Olson 1968: Fm-3m, a=5.167 A. Th-N = 2.58 A."
    },
    {
      "formula": "Th3N4",
      "cohort": "v10",
      "category": "Th3N4",
      "coord": 7,
      "pair": "Th-N",
      "exp_nn_pm": 245.0,
      "pred_nn_pm": 243.34,
      "abs_err_pm": 1.66,
      "pct_err": -0.678,
      "source": "Benz 1968: R-3m Th3N4-type, a=3.875 A c=27.39 A. Th-N avg = 2.45 A."
    },
    {
      "formula": "K2NiF4",
      "cohort": "v10",
      "category": "K2NiF4",
      "coord": 6,
      "pair": "Ni-F",
      "exp_nn_pm": 200.0,
      "pred_nn_pm": 200.1,
      "abs_err_pm": 0.1,
      "pct_err": 0.05,
      "source": "Balz 1953: I4/mmm K2NiF4 layered perov-like, a=4.006 A, c=13.076 A. Ni-F = 2.003 A. (Layered analogue of perov.)."
    },
    {
      "formula": "Sr2RuO4",
      "cohort": "v10",
      "category": "K2NiF4",
      "coord": 6,
      "pair": "Ru-O",
      "exp_nn_pm": 194.0,
      "pred_nn_pm": 201.69,
      "abs_err_pm": 7.69,
      "pct_err": 3.964,
      "source": "Walz 1993: I4/mmm K2NiF4 layered perov, a=3.870 A, c=12.74 A. Ru(IV)-O = 1.94 A in-plane."
    },
    {
      "formula": "La2NiO4",
      "cohort": "v10",
      "category": "K2NiF4",
      "coord": 6,
      "pair": "Ni-O",
      "exp_nn_pm": 193.0,
      "pred_nn_pm": 203.56,
      "abs_err_pm": 10.56,
      "pct_err": 5.474,
      "source": "Rodriguez-Carvajal 1991: I4/mmm, a=3.857 A, c=12.652 A. Ni-O(in-plane) = 1.928 A."
    },
    {
      "formula": "ScB2",
      "cohort": "v10",
      "category": "AlB2",
      "coord": 12,
      "pair": "Sc-B",
      "exp_nn_pm": 254.0,
      "pred_nn_pm": 254.05,
      "abs_err_pm": 0.05,
      "pct_err": 0.018,
      "source": "Pauling File: P6/mmm AlB2-type, a=3.146 A, c=3.518 A. Sc-B = 2.54 A."
    },
    {
      "formula": "YB2",
      "cohort": "v10",
      "category": "AlB2",
      "coord": 12,
      "pair": "Y-B",
      "exp_nn_pm": 268.0,
      "pred_nn_pm": 277.85,
      "abs_err_pm": 9.85,
      "pct_err": 3.677,
      "source": "Pauling File: P6/mmm, a=3.305 A, c=3.844 A. Y-B = 2.68 A."
    },
    {
      "formula": "FeAl2O4",
      "cohort": "v10",
      "category": "Spinel",
      "coord": 6,
      "pair": "Al-O",
      "exp_nn_pm": 187.0,
      "pred_nn_pm": 191.37,
      "abs_err_pm": 4.37,
      "pct_err": 2.336,
      "source": "Hill 1979 hercynite: Fd-3m normal spinel, a=8.135 A. Al(B-site oct) - O = 1.87 A."
    },
    {
      "formula": "NiCr2O4",
      "cohort": "v10",
      "category": "Spinel",
      "coord": 6,
      "pair": "Cr-O",
      "exp_nn_pm": 199.0,
      "pred_nn_pm": 198.63,
      "abs_err_pm": 0.37,
      "pct_err": -0.185,
      "source": "Wickham 1959: I4_1/amd tetragonal-distorted spinel, a=5.832 A, c=8.430 A. Cr-O avg = 1.99 A."
    },
    {
      "formula": "ZnAl2O4",
      "cohort": "v10",
      "category": "Spinel",
      "coord": 6,
      "pair": "Al-O",
      "exp_nn_pm": 191.0,
      "pred_nn_pm": 191.37,
      "abs_err_pm": 0.37,
      "pct_err": 0.193,
      "source": "Cooley 1965 gahnite: Fd-3m normal spinel, a=8.085 A. Al-O = 1.91 A."
    },
    {
      "formula": "BaSnO3",
      "cohort": "v10",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 208.0,
      "pred_nn_pm": 209.35,
      "abs_err_pm": 1.35,
      "pct_err": 0.65,
      "source": "Megaw 1946: Pm-3m cubic perov, a=4.117 A. Sn(IV)-O = a/2 = 2.058 A."
    },
    {
      "formula": "SrSnO3",
      "cohort": "v10",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 204.0,
      "pred_nn_pm": 209.35,
      "abs_err_pm": 5.35,
      "pct_err": 2.623,
      "source": "Vegas 1986: Pbnm distorted perov, a=5.708 A. Sn(IV)-O avg = 2.04 A."
    },
    {
      "formula": "CaSnO3",
      "cohort": "v10",
      "category": "Perovskite",
      "coord": 6,
      "pair": "Sn-O",
      "exp_nn_pm": 201.0,
      "pred_nn_pm": 207.31,
      "abs_err_pm": 6.31,
      "pct_err": 3.14,
      "source": "Vegas 1986: Pbnm, a=5.519 A. Sn(IV)-O avg = 2.01 A."
    }
  ]
}