Wetting and drying transitions at a fluid-wall interface: Density-functional theory versus computer simulation

This paper reports on studies of wetting phase behavior and interfacial density profiles of square-well fluid adsorbed at a square-well wall. At a specific drying transition, a comparison is made between computer-simulation data and coarse-grained density-functional theory. The successes and failures of this comparison form the basis of a detailed discussion of the strengths and weaknesses of the two approaches, as presently implemented, and proposals are made for removing the current ambiguities. In addition, density-functional theory is used to map out the global interfacial phase behavior at bulk liquid-vapor coexistence, in terms of the fields {T,εw} where T denotes temperature and εw is the strength of the attractive wall-fluid interaction. Particular attention is paid to questions of statistical-mechanical consistency in the form of exact sum rules.