Percus-Yevick results for a binary mixture of hard spheres with non-additive diameters

Abstract

We have carried out extensive calculations, within the Percus-Yevick approximation, for a binary mixture of hard spheres with negative departures from additivity in their hard sphere diameters. The results presented in this work are restricted to the case of equal size spheres at equimolar composition.

We have calculated the virial equation of state and show that the more negative the non-additive parameter, the better the agreement between our results and the Monte Carlo results of Adams and McDonald. Moreover, we find no evidence of a phase transition for this system.

Our calculations of the radial distribution functions gij(r) show clearly the important changes brought about by non-additivity, in particular, to g ₁₂(r). We have also calculated the number-concentration partial structure factors, which highlights the ordering effects taking place in the system as a results of non-additivity.

Our results indicate that, if size difference between the hard spheres is included, non-additive hard spheres with negative non-additive parameter, may be good candidates to model the partial structure factors of liquid binary alloys of the intermediate type, such as CuSn.