Density Functional Theory Based on the Universality Principle and Third-Order Expansion Approximation for Adhesive Hard-Sphere Fluid near Surfaces

Abstract

The high-order perturbative density functional theory (Phys. Rev. E 2000, 61, 2704) was reformulated to be adapted for a nonuniform Lennard-Jones fluid with an attractive tail included in the interaction potential as a whole. The second-order direct correlation function of a uniform adhesive hard-sphere fluid was divided into a hard-sphere-like part and an attractive-tail part, and then the density functional formalism based on the universality principle and bridge function concept was employed to treat the nonuniform first-order direct correlation function for the hard-sphere-like part. The reformulated high-order perturbative density functional theory was employed to treat the attractive-tail part for the nonuniform case. The two parts were added together to construct the nonuniform first-order direct correlation function of the adhesive hard-sphere fluid. Then, the ensued result was substituted into the density profile equation in the density functional theory to predict the nonuniform density distribution profile and the contact density for an adhesive hard-sphere fluid subject to an external field. Good agreement with the corresponding computer simulation data was obtained.