First-Order Perturbation Theory for the Distribution Functions of a Dense Fluid

Abstract

A first-order expansion of the Percus-Yevick functional is derived for the properties of a real fluid as a perturbation about a hard-sphere reference fluid. The resulting expression is an integral equa ion relating the real fluid distribution functions and intermolecular potential to those of the reference fluid. Use of a realistic approximation in calculating the integral in the Ornstein-Zernike equation leads to real-fluid distribution functions that are in closer agreement with molecular dynamics results than those of the usual first-order Percus-Yevick equation.