Electrostatic potential mapping using hybridization displacement charge: Atomic parameters and transferability of charge and potential

Abstract

Molecular electrostatic potential MEP maps and MEP-derived charges for certain molecules were studied by the ab initio approach using the 6-31G basis set.Ž . These results were used to obtain the parameters K and for fluorine, sulfur, and Ž . chlorine required for the hybridization displacement charge HDC calculations employing the MNDO and AMI methods. The HDC combined with Lowdin charges, distributed continuously in three-dimension spherically and symmetrically, were shown to reproduce ab initio MEP features of molecules fairly well. This method of computing the MEP was applied to two molecules of pharmacological importance, namely, dimaprit and mustard gas. It is shown by studying the cis and trans forms of two amino acids that transferability of the MEP is appreciably less acceptable than that of charges in going from one conformation to the other.