Table : Average RRMS errors (unitless) of ESPs, relative to reference QM ESPs, computed using partial charges derived from one conformer (column 1) and tested for a second conformer (columns 2 and 3), for electrostatic models AM1-BCC, AM1-BCC-dPol, and RESP. As shown in Table2, AM1-BCC-dPol provides consistently low errors (< 1%) across both the training and test conformers. RESP-dPol provides slightly greater accuracy overall when trained and tested on the same conformation (diagonal elements of each subtable), but less accuracy when trained on one conformer and tested against the conformer (off-diagonal elements). These increased errors presumably reflect overtraining. The nonpolarizable AM1-BCC model is less accurate than AM1-BCC-dPol in all four cases and less accurate than RESP-dPol in all but one case. Overall, these results suggest that our AM1-BCC-dPol model is more transferable and accurate than AM1-BCC, at least in part because its inducible dipoles respond appropriately to changing electrostatic environments. The simplicity, transferability, and accuracy afforded by AM1-BCC-dPol make it an attractive charge model for use in MD simulations where conformational charges play an important role. ).