Structures of binary hard-core repulsive Yukawa mixtures near solid surfaces from DFT

A free energy density functional theory (DFT) has been used to investigate the density profiles of binary hard-core repulsive Yukawa (HCRY) mixtures under the influence of various external fields. The representation of the excess Helmholtz free energy functional was based on the perturbation theory, where a weighted density approximation (WDA) theory, proposed by Kierlik and Rosinberg, was applied for the hard-core repulsive interaction and a mean field theory (MFT) was used for the long-range dispersion one. To test the validity of the DFT, the grand canonical ensemble Monte Carlo (GCMC) simulations were carried out to obtain the density profiles of binary HCRY mixtures under different bulk densities, hard-core diameters, and energy parameter ratios. The DFT calculations are in quite good agreement with the GCMC simulations.