Perturbation Calculations in Equilibrium Statistical Mechanics. I. Hard Sphere Basis Potential

Abstract

A study is made of the effect of potential perturbations on the equilibrium properties of a hard sphere system at both high and low densities. The perturbation is evaluated beyond the first‐order term for the second and third virial coefficients to estimate the region of convergence. The results of the first‐order perturbation from the virial expansion, superposition theory, and free‐volume theory are compared. A comparison with experimental data is made to show the applicability of this perturbation from a hard sphere potential to the estimation of the equilibrium properties of a great variety of gases at moderately high temperatures.