The equation of state of hard-spherocylinder fluid mixtures

This work reports the density dependence of the compressibility factor of fifty binary mixtures of prolate spherocylinders, obtained by Monte Carlo simulation. The results are combined with other simulation results, including those for the pure fluid, to test existing equations of state (EOS) for the mixture. Best results are obtained with the EOS by Pavlicek and co-workers (T. Boublik and I. Nezbeda, Collect. Czech. Chem. Commun., 1986., 51, 2301, eqn. 5.79). We suggest a modification in this EOS, which improves its accuracy. At the same time, the new EOS still reduces to the Boublik-Mansoori-Carnahan-Starling equation of state for the particular case of hard-sphere mixtures. The proposed EOS is able to reproduce with good accuracy the compressibility factor of binary mixtures with 1 less than or equal to gamma less than or equal to 4, where gamma is the ratio of maximum length to breadth of each species, and with a ratio of the largest spherocylinder volume to the smallest one of up to 10.