The calculation of correlation functions in fluids by a weighted density concept

Abstract

An exact equation for the pair correlation function of fluids is derived by density functional methods. Comparing this result with the hypernetted chain (HNC) equation we propose a weighted density approximation for the so-called bridge function that improves the ordinary HNC theory. For a hard sphere fluid this method leads to thermodynamically more consistent results than the HNC, Percus-Yevick (PY) and Rogers-Young (RY) approximations. Adding an attractive potential to the hard sphere repulsion we obtain better correlation functions than can be found with the HNC and the reference HNC (RHNC) approximation.