Thermodynamics of pseudo-hard body mixtures

Thermodynamic properties of binary mixtures of hard spheres of various size and pseudo-hard bodies, mimicking the short-range non-additive repulsive interactions in realistic models of water, have been determined over the entire concentration range using standard NVT Monte Carlo simulations. Virial coefficients of the mixture have also been computed. Having no other theoretical tool currently available, a perturbed virial expansion is examined with respect to its potential to estimate/predict the properties of the mixture without resorting to any fitting of simulation data. The perturbed virial expansion is found to perform quite accurately for the mixtures containing larger spheres, whereas for small spheres dissolved in water the result is only qualitatively correct.