Combining rules for intermolecular potential parameters. I. Rules for the Dymond-Alder potential

Abstract

A new combining rule for the collision diameters of the Dymond-Alder pair potential function has been introduced. The rule was obtained by considering the long-range repulsive interactions of noble gas atoms, and gives the parameter for an interaction between unlike molecules as a weighted algebraic mean of those for the corresponding like-pair interactions. It is shown that the rule works very well in predicting the second virival coefficients of Ne–Ar, Ar–Kr, and Ar–CH4 mixtures and the binary diffusion coefficients of Ne–Ar, Ne–Kr, Ne–Xe, Ar–Kr, and Ar–Xe mixtures when it is used in conjunction with the previously proposed rule for the potential well-depth parameters, εij = 2εiiεjj/(εii + εjj).