Dispersion energy in rare gas dimers from an ab initio perturbative procedure: Ne + Ne, Ar + Ar

Abstract

The dispersion energy between two neon and two argon atoms is computed from an ab initio perturbative procedure not based on the multipole expansion. A comparison with the multipole expansion provides C 6 = 5.36 for Ne and 76.6 for Ar. It is seen that one d polarization function provides the main part of the C 6 R −6 contribution, the exponent of this function probably being related to the polarizability of the molecule. The multipole expansion seems acceptable up to the van der Waals minimum but quite invalid for smaller distances, and doubtful at the van der Waals minimum itself.