On Pairwise Additivity of London-van der Waals Forces —The Drude Model Calculation—

Abstract

Deviations from pairwise additivity of dispersion energies between two parallel linear chains and between two parallel square lattices (for the latter, an asymptotic form at large separation) are calculated with a Drude (harmonic oscillator) model. In the case of normal paraffin crystal the deviation is practically negligible in the neighborhood of the equilibrium separation on the contrary to a conclusion by Zwanzig. The fact may be a reason why the assumption of pairwise additivity has been successfully applied to paraffin crystal and graphite lattice.