SELF-CONSISTENT THEORY OF ELASTIC PROPERTIES OF STRONGLY ANHARMONIC CRYSTALS .2. PROPERTIES OF HEAVY RARE-GAS SOLIDS

The method developed in the preceding papers has been used to calculate the full set of equilibrium thermodynamic properties of solid Ar, Kr and Xe at normal pressure. We have used various pairwise interatomic potentials taking into account the three-body Axilrod-Teller forces. For Ar and Kr the multiparameter potentials proposed by Barker et al. provide the best fit to available experimental data, and for Xe the old Lennard-Jones potential does this. Deviations from the Cauchy relations are discussed. Temperature dependencies of the stability coefficients and anisotropy have received much attention. In the unstable point that is about 1.35-1.45 times larger than the experimental melting temperature of each crystal, the isothermal bulk modulus goes to zero (and the thermal expansion coefficient and the isobaric specific heat tend to infinity). Other stability coefficients remain finite and positive.