Densityhyphen;functional perturbation theory of inhomogeneous simple fluids

摘要

The meanhyphen;field approximation, widely used in the nonlocalhyphen;densityhyphen;functional theories of inhomogeneous simple fluids, is reexamined. Comparing its predictions of the density profiles of a Lennardhyphen;Jones fluid near a hard wall with those of Monte Carlo simulations reveals that the approximation is qualitatively incorrect at low densities and quantitatively inaccurate at intermediate and high densities. A densityhyphen;functional perturbation theory is proposed. It combines the nonlocalhyphen;densityhyphen;functional model of an inhomogeneous hardhyphen;sphere system with the Barkerndash;Henderson secondhyphen;order perturbation theory of uniform simple fluids. It also takes into account the softness of the shorthyphen;range repulsive potential. The new theory is shown to be qualitatively correct and quantitatively more accurate over the whole range of liquid densities. The effects of the pair potential truncation and the selfhyphen;consistency of the nonlocalhyphen;densityhyphen;functional theories are discussed.