While both the MAE and RMSE values are improved, transformations 11 to 14 and 14 to 15 had the same convergence issues as with the restraint approach. However, in the UAFF simulations, the DCH site remains much closer to the crystal structure. This is likely due to not only the more accurate partial charges of zinc-coordinating residues but also due to the more restrained equilibration protocol. In all transformations, apart from 16 to 9 and 16 to 15, the DCH site is tetrahedral (as in the crystal structure) with a bidentate ligand.