Polarizability and Second Dielectric Virial Coefficient of Interacting He Atoms

Abstract

The polarizability $\alpha$ of the pair of interacting He atoms has been calculated by Hartree–Fock perturbation theory, both coupled and uncoupled. A basis of 16 Gaussians was used, eight centered on each atom. Good convergence was obtained in the region of overlap between one and six atomic units internuclear separation, $R$ . Values of $\alpha$ for large separations were obtained by extrapolation using an $R^{\text{−6}}$ dependence as predicted by previous long‐range calculations. The effect of the interatomic interaction on the second dielectric virial coefficient was then calculated using the radial distribution function based on empirical Lennard‐Jones parameters. The results show that the effect of overlap and exchange do not sufficiently counteract the positive deviation caused by the van der Waals interaction to produce the substantial negative value as measured by Orcutt and Cole.