Two-body integrals for hard sphere fluid based on Tang–Lu RDF expression

Abstract

Two-body integral with hard sphere reference fluid is of significance in thermodynamic modelling with perturbation theory. In this paper, the two-body integral is recalculated by using Tang–Lu radial distribution function (RDF) expression, which is superior to P–Y RDF in representing the structure of hard sphere fluid in whole density region and especially in contact-distance region. It is found that the two-body integral values calculated with Tang–Lu RDF are between those of Larsen et al.’s and Henderson et al.’s, and their difference is negligible. In order to investigate the accuracy of two-body integrals, properties of Lennard–Jones fluid are calculated with B–H perturbation theory under local-compressible approximation and compared with computer simulation results. It is shown that the accuracy of internal energy and compressibility calculated with two-body integrals of this paper and with Larsen et al.’s are 6.78, 8.60, 6.85 and 9.08%, respectively for 170 computer simulation data. As a whole, the accuracy of the present two-body integral with Tang–Lu RDF is a little superior to that of Larsen et al.’s.