EFFECT OF MOLECULAR ELONGATION ON LIQUID VAPOR PROPERTIES - COMPUTER-SIMULATION AND VIRIAL APPROXIMATION

The effect of molecular elongation on the liquid-vapour coexistence curve for fluids modelled by the anisotropic Gay-Berne potential has been studied by using the Gibbs ensemble Monte Carlo simulation technique. It is shown that there is a departure from the principle of corresponding states. From the coexistence curves, the critical temperature, density and pressure for two elongations have been determined. Simple arguments based on a third virial coefficient expansion are shown to give a farily good estimation of the critical temperature and pressure, but underestimates substantially the critical density. This approximation is also used to study the effect of other intermolecular parameters on the critical values of these model fluids.