WETTING AND DRYING TRANSITIONS AT A FLUID-WALL INTERFACE - DENSITY-FUNCTIONAL THEORY VERSUS COMPUTER-SIMULATION .2.

This paper reports on studies of wetting phase behavior and interfacial structure of square-well fluid adsorbed at square-well walls. Choosing a particular wetting isotherm at bulk liquid-vapor coexistence, we present our final and complete comparison between molecular-dynamics (MD) simulation and weighted-density-approximation (WDA) density-functional theory. The properties of wall-liquid, wall-vapor, and liquid-vapor interfaces are measured and used to determine contact angles and to locate the positions and order of interfacial phase transitions (wetting and drying). Due to the presence of a suitable collective mode, it was possible to directly observe the collective dynamics of the fluctuation-induced first-order drying transition in MD simulation. A practical implementation of contact-angle measurement by generalized WDA density-functional theory is detailed, enabling one to input the bulk equation of state as a boundary condition. An attempt is made to gauge the generality of our results by comparison with simulation data from other systems and with alternative versions of WDA theory.