# Explicit Solvation Error Breakdown (Public, 2026-03-05)

## Headline

- Current MAE: **0.3295 kcal/mol** (**1.3787 kJ/mol**)
- Relative to the prior benchmark cycle, error decreased by **0.0151 kcal/mol**.

## Largest Remaining Error Contributors (by total absolute error)

| Chemotype | n | MAE (kcal/mol) | Sum AE (kcal/mol) |
|---|---:|---:|---:|
| general | 196 | 0.362 | 70.89 |
| phenolic_polar_aromatic | 30 | 0.418 | 12.53 |
| hydrophobe | 36 | 0.376 | 13.55 |
| ester_rich | 46 | 0.293 | 13.48 |
| aryl_hydrophobe | 36 | 0.322 | 11.59 |
| chlorinated_hydrophobe | 22 | 0.471 | 10.37 |
| alkane_hydrophobe | 42 | 0.244 | 10.26 |
| nitro | 25 | 0.300 | 7.50 |

## Highest-MAE Chemotypes (n >= 5)

| Chemotype | n | MAE (kcal/mol) |
|---|---:|---:|
| halophenol_like | 11 | 0.581 |
| uracil_like | 7 | 0.586 |
| fluoro_haloalkane | 6 | 0.576 |
| phenolic_polar_aromatic | 30 | 0.500 |
| chlorinated_hydrophobe | 22 | 0.471 |
| alkoxy_phenol | 5 | 0.332 |

## Public Improvement Notes

- Largest improvements are in aromatic polar families and selected alkoxy-phenol families.
- Remaining gaps are concentrated in halogen-rich and hetero-aromatic edge chemistry.
- Small-support chemotypes (very low n) are monitored with conservative interpretation.

## Next Public Focus Areas

1. Improve anisotropic nonbonded treatment in halogen-rich families.
2. Improve hydrogen-bond directionality handling in hetero-aromatic families.
3. Continue splitting broad buckets into higher-support subfamilies for calibration stability.

Public export note: this file intentionally omits internal implementation formulas and internal model-tuning identifiers.