Dispersion forces at arbitrary distances

Abstract

The formalism of Boehm and Yaris is used to evaluate explicitly the leading term of the London dispersion force between closed-shell atoms. Instead of using the usual multipole expansion, which breaks down at intermediate internuclear distances, an analytic representation of the Born amplitude together with a general angular momentum analysis is used. As a result, expressions are obtained which reduce to the usual dispersion forces at large distances and are finite at all distances.