Anharmonic phonon spectrum and heat capacities of solid neon

Abstract

A pseudoanharmonic central-force rigid-atom model has been used to study the phonon spectrum, dispersion curves and heat capacities of solidified neon. The model uses a Buckingham-type exponential potential function, the parameters of which are derived from crystal data. The effect of zero-point vibrations has been taken into account by an iteration method and the contributions of cubic and quartic terms of the potential-energy expansion are included at 0 °K, through Helmholtz free energy. The effect of zero-point anharmonicity over frequency spectrum, dispersion of phonons and heat capacities is seen to be appreciable. The (ϑ, T) curve has a shape similar to other theoretical ones. The agreement between computed and observed specific heats is good. The inherent defects of the model have also been pointed out.