Spatial structure and thermodynamic properties of a classical fluid of hard spheres with attractive square wells

Abstract

The spatial structure and the thermodynamic properties of a classical fluid of hard spheres with attractive square wells are analyzed, based on the Percus-Yevick equation reformulated by Baxter. The equation of state, the isothermal compressibility, the internal energy, the direct correlation function, the radial distribution function, and the structure factor are evaluated over a wide range of temperatures and densities when the width of the attractive square well is half the diameter of the hard core. The temperature- and the density-dependent behaviors of the obtained quantities are discussed. The equation of state is compared with theoretical results obtained by other authors. The pressures calculated via the compressibility equation are in satisfactory agreement with the pressures obtained from computer experiments both at the supercritical temperature kT/ε=3.333 and at the subcritical temperature kT/ε=1.17. Attempts are made to fit the pressures calculated via the compressibility equation to the experimental pressures for gases and liquids. The satisfactory fit between the theoretical and the experimental pressures is shown to be made for rare gases and hydrocargons. The fluid structure is shown to be largely dominated by the repulsive core of the potential when the density is high.