Intermolecular forces between large molecules

Abstract
The long-range interaction between large molecules with localized electrons is written as the sum of individual interactions between localized charge distributions. Using minimal basis set ab initio Hartree-Fock wavefunctions the parameters needed to compute these interactions are obtained for water, methane and ethane. Interactions between pairs of these molecules are computed for various orientations to demonstrate the complex orientational dependence and the relative magnitudes of the various terms.