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Virial coefficients and demixing of athermal nonadditive mixtures

G. Pellicane·F. Saija·C. Caccamo·P. V. Giaquinta
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Abstract

We compute the fourth virial coefficient of a binary nonadditive hard-sphere mixture over a wide range of deviations from diameter additivity and size ratios. Hinging on this knowledge, we build up a $y$ expansion [B. Barboy and W. N. Gelbart, J. Chem. Phys. {\bf 71}, 3053 (1979)] in order to trace the fluid-fluid coexistence lines which we then compare with the available Gibbs-ensemble Monte Carlo data and with the estimates obtained through two refined integral-equation theories of the fluid state. We find that in a regime of moderately negative nonadditivity and largely asymmetric diameters, relevant to the modelling of sterically and electrostatically stabilized colloidal mixtures, the fluid-fluid critical point is unstable with respect to crystallization.

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G. Pellicane, F. Saija, C. Caccamo, P. V. Giaquinta. 2007-03-01. Virial coefficients and demixing of athermal nonadditive mixtures. https://doi.org/10.1021/jp070277m

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