Exp-6 Cell Model Calculations for the Inert Gas Solids. I. Characterization of Pair Potential Parameters with and without the Triple-Dipole Term

Abstract

A quantum version of the Lennard-Jones and Devonshire cell model is developed for the exp-6 pair potential. The three characteristic reduction parameters of this potential are determined from zero-point thermodynamic data for solid neon, argon, krypton, and xenon. Calculations are made with and without the consideration of the long-range triple-dipole term in the static lattice potential. Consideration is then given to the available second virial low density gas data for argon and krypton. It is shown that those parameters determined with the inclusion of the three-body term given a good prediction of the second virial data. These parameter values are considerably different from those obtained by a direct fit of the potential to the virial data. It is nevertheless suggested that using these parameters the exp-6 potential acts as an acceptable pair potential.