Simulation results and corresponding states correlation for pure rigid molecular fluids

Abstract

The compressibility, configurational internal and Helmholtz free energies, and the site-site and angle-averaged pair correlation functions are reported for six two-site and three-site Lennard-Jones molecules at a total of 212 state points computed by Monte Carlo simulation. This extensive data set can be used to test equations of state and statistical mechanical theories. A three-parameter corresponding states principle based on perturbed-hard-chain theory, using previously derived equations of state for the monatomic Lennard-Jones fluid, was used to correlate the simulation data with satisfactory accuracy. From the correlations and a simplified perturbation theory analysis, it is found that while the perturbed-hard-chain corresponding states method provides a reasonable correlation of the simulation data for small, rigid nonspherical molecules, the corresponding states parameters must have a different interpretation from the one usually given. Finally, the phase diagrams and critical properties of the molecular fluids studied here are reported, computed using the equations of state developed from the perturbed-hard-chain analysis. The critical properties compare well with previous results obtained by others using perturbation theory and integral equations.