RESEARCH NOTE Some results for the Ballone-Pastore-Galli modification of the Martynov-Sarkisov closure for hard spheres

Abstract

Ballone, P. G., Pastore, G., and Galli, G., 1986, Molec. Phys., 59, 275 have proposed a simple modification of the Martynov–Sarkisov (MS) closure where a parameter s (2 in the MS closure) is adjustable. A systematic procedure for determining s from the known and easily determined value of the bridge function at low densities and for zero separation is given. The resulting value is s = 47 /32. This value of s gives improved values for the correlation functions for zero separation but the MS value, s = 2, gives better values for the correlation functions at contact. For hard spheres, at least, a single value of s cannot yield a satisfactory correlation function. The Verlet closure is preferable in this respect.