Atomic charges derived from semiempirical electrostatic potentials; an interaction energy method

Abstract

A method for calculating molecular electrostatic potentials using the semiempirical MNDO and AM1 Hamiltonians is presented. The electrostatic potential within the semiempirical framework is obtained as the first-order interaction energy between a unit positive charge (i.e. a hydrogen nucleus) and the molecule. The atomic charge distributions derived from such electrostatic potentials are of similar quality to those obtained as expectation values of the Coulomb potential operator using semiempirical wavefunctions derived from the MNDO or AM1 density matrices. The method requires trivial amounts of computer time and therefore should be well suited for deriving atomic charge models of large biological molecules for use in molecular mechanics and molecular dynamics simulations.