Equilibrium properties of simple molecular fluids

Abstract

The application of thermodynamic perturbation theory in which all tensor interactions are taken as perturbation of the pair central potential to the computation of the equilibrium properties of uniform molecular fluids is considered. Comparisons with experiment are made for nitrogen, oxygen, carbon monoxide, carbon dioxide, and methane. Theoretical expressions are given and calculations made for Helmholtz free energy, configurational energy, entropy, and pressure, taking into account the influence of permanent electric multipole moments, induced dipole moments, anisotropic dispersion, and overlap forces. The influence of three-body nonadditive interaction arising from dispersion and classical electric induction interactions between asymmetric molecules on the thermodynamic properties is also considered. Excellent agreement with experiment is obtained for all systems.