Molecular electrostatic charge models: a topographical approach

Abstract

Electrostatic charge models for molecules have been developed by employing the critical topographical features of the molecular electrostatic potential (MESP) as the "fitting" criterion. These models include one or more spherical Gaussians for incorporating the continuous electron-charge distribution in addition to the positive valued point charges representing the nuclei. The model parameters (point charges, the orbital exponents, and Gaussian centers) are optimized so as to mimic the extremal characteristics of the corresponding quantum chemical MESP. The test cases reported here include methane, ethylene, and methanol molecules. The charge models developed using the present method are seen to satisfactorily reproduce the ab initio MESP and its extremal features.