Reproduction of ab Initio Electrostatic Potential with Classical Fractional Point Charges

Abstract

New additional charge sets, which were added to correct the electrostatic potential (ESP) values on the van der Waals molecular surface using Mulliken net atomic charges, were found to reproduce ab initio ESP with the STO-3G basis set. The charge sets were obtained for fundamental small molecules (water, ammonia. methane. ethane, and benzene). Lone pair regions of oxygen and nitrogen atoms show remarkable improvement, while pi electrons do not contribute much to ESP. The present work opens a way for treating large molecules of biological interest.