Studies on phase equilibria of two-centre Lennard-Jones fluids

Abstract

Several results concerning the phase equilibria of two-centre Lennard-Jones (2CLJ) fluids are presented. Firstly, a comparison of chemical potential values for the elongation L = 0·63 obtained from perturbation theory shows qualitative agreement with the simulation results of Romano and Singer and excellent agreement with results of Guillot and Guissani except at the highest density. The complete saturation curve of the 2CLJ-0·63 fluid is then calculated by combining the Romano-Singer results, the Haar-Shenker-Kohler equation and perturbation theory. For the 2CLJ-fluids with L = 0·05, 0·10, and 0·20 the low-temperature saturation curves are calculated by perturbation theory as well as the pseudocritical points. At that point the packing fraction of the hard molecular cores has the constant value η = 0·165 in going from L = 0 to L = 0·3292 and falls off slightly for higher elongations. The reduced hard sphere diameter d/σ, however, shows a distinct minimum at about L = 0·27.