Modifications of the SP-MC method for the computer simulation of chemical potentials: ternary mixtures of fused hard sphere fluids

Abstract

The efficient recently proposed scaled particle Monte Carlo (SP-MC) computer simulation method for calculating the chemical potentials of hard body fluids at very high densities is modified and extended, with the derivation of the modified method for pure hard spheres and their mixtures, and for pure hard diatomics. The method is extended to a ternary mixture of tangent heteronuclear diatomics and their constituent hard spheres (the method is extended readily to mixtures of arbitrary fused hard sphere molecules and their constituent spheres). Detailed calculations have been made for a ternary system reported in the literature, composed of hard spheres of different diameters and their tangent diatomics. The present method is much more efficient than previous approaches. It was found that the difference in excess chemical potentials of the diatomics and the spheres is essentially independent of composition, a feature exhibited also by the Boublík–Nezbeda hard body equation of state, which slightly underestimates the simulation values.