Integral equation theory for the equilibrium properties of the semiclassical fluid with hard-core potential

Abstract

Quantum corrections to the radial distribution function (RDF) and thermodynamic properties for semiclassical fluids whose molecules interact via pair potentials which are nonanalytic functions of the intermolecular separation are calculated by means of statistical mechanical perturbation theory using the extended Percus-Yevick (PY) and hypernetted-chain (HNC) theories. Expressions are obtained in terms of effective two-body potential which includes quantum mechanical corrections. One attractive feature of this method is that the higher order quantum corrections, in principle, are as easily calculated as the first order term. Numerical results are given for the first- and second-order corrections to the free energy and to the pressure, and for the first-order correction to the RDF. Significant features are the large increase in quantum corrections with increasing density, and the qualitative difference that quantum mechanics makes to the RDF near the hard core.