Modified cell model for liquids: order defects and intermolecular potentials

Abstract

On the basis of a cell model, an explicit introduction of coordination defects is possible. In binary mixtures, consideration of coordination defects gives only a small correction to the thermodynamic excess properties of mixing. The excess free energy is lowered, and its concentration dependence is influenced in about the same way as by using the quasichemical approximation. Furthermore, the modified cell model has been used to calculate the thermodynamic properties of solid and liquid argon, employing a Kihara pair potential. Comparison is made with previous calculations using a Lennard-Jones pair potential. The parameters of the Kihara potential giving the best fit at high densities differ markedly from those giving the best fit for transport properties and second virial coefficients. The influence of the exact form of the pair potential on the thermodynamic properties is not very important.