Publication | Closed Access
Fast, efficient generation of high-quality atomic charges. AM1-BCC model: I. Method
96
Citations
0
References
2000
Year
Am1-bcc MethodEngineeringOrganometallic ElectrochemistryComputational ChemistryChemistryAm1-bcc ModelCharge TransportHigh-quality Atomic ChargesEfficient GenerationBcc ParametersCharge SeparationIon EmissionCharge ExtractionCharge Carrier TransportPhysicsMolecular ElectrochemistryChemical BondAtomic PhysicsQuantum ChemistryNatural SciencesApplied Physics
AM1‑BCC rapidly generates high‑quality atomic charges suitable for condensed‑phase simulations. The authors aim to extend AM1‑BCC into a universal, consistent charge model for all organic and biological molecules. BCC parameters were fitted to HF/6‑31G* electrostatic potentials of 45 diverse compounds using 41 parameters, following a consensus BCI formalism. AM1‑BCC produces charge sets comparable to HF/6‑31G* ESP‑derived charges, with only 0.01–0.02 a.u. higher RMS error, while being faster and more stable.
The AM1-BCC method quickly and efficiently generates high-quality atomic charges for use in condensed-phase simulations. The underlying features of the electron distribution including formal charge and delocalization are first captured by AM1 atomic charges for the individual molecule. Bond charge corrections (BCCs), which have been parameterized against the HF/6-31G* electrostatic potential (ESP) of a training set of compounds containing relevant functional groups, are then added using a formalism identical to the consensus BCI (bond charge increment) approach. As a proof of the concept, we fit BCCs simultaneously to 45 compounds including O-, N-, and S-containing functionalities, aromatics, and heteroaromatics, using only 41 BCC parameters. AM1-BCC yields charge sets of comparable quality to HF/6-31G* ESP-derived charges in a fraction of the time while reducing instabilities in the atomic charges compared to direct ESP-fit methods. We then apply the BCC parameters to a small “test set” consisting of aspirin, d-glucose, and eryodictyol; the AM1-BCC model again provides atomic charges of quality comparable with HF/6-31G* RESP charges, as judged by an increase of only 0.01 to 0.02 atomic units in the root-mean-square (RMS) error in ESP. Based on these encouraging results, we intend to parameterize the AM1-BCC model to provide a consistent charge model for any organic or biological molecule. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 132–146, 2000