(243c) A Closure-Based Density Functional Theory for the Depletive Adsorption of Fluids With Attraction

A new closure-based density functional theory is proposed for fluids with attractive and/or repulsive interactions.  We pay special attention to the cases where depletion of the gas density occurs at the wall. Applications are made to the Lennard-Jones fluid and the Yukawa potential with a hard core.  The closure is based on the exact third-order Ornstein-Zernike relation [1]. We discover that the bridge clusters is of the functional type dependent on the indirect correlation function, B = B[γ]. Upon invoking reasonable approximations to the triplet correlation functions, we obtain accurate prediction for the adsorption where fluid molecules are rarified compared to the bulk fluid when verified with machine data [2].

[1].. L. L. Lee, The correlation functions of classical fluids III.  The method of partition function variations applied to the chemical potential: cases of PY and HNC2, Journal of Chemical Physics 60, 1197 (1974).

 [2].. L. L. Lee, “Constructing a new closure theory based on the third-order Ornstein-Zernike equation and a study of the adsorption of simple fluids”, Journal of Chemical Physics 135, 204706 (2011).