An analytic equation of state and structural properties of nonadditive hard sphere mixtures

摘要

We present a new analytic fluidhyphen;phase equation of state (EOS) of binary nonadditive hard sphere mixtures having equal collision diameters (d11=d22=d) between like species, but having an unequal collision diameter (d12) between unlike species. For this purpose, we have generated EOS data by Monte Carlo simulations over a wide range of density, composition, andd12. The analytic EOS produces reliable results ford12ge;dandd12d. These results are used to test the van der Waals onehyphen;fluid model of mixtures and the modified Martynov and Sarkisov integral equation lsqb;Mol. Phys.59, 275 (1986)rsqb;. Shorthyphen;range structures at high density reveal a broad peak in heterocoordinated packing and a minimum in homocoordination asd12is reduced belowd. The present analysis also strongly indicates, in agreement with available data, a fluidndash;fluid phase change at high density whend12gsim;d.