Further studies of prewetting transitions via Monte Carlo simulation

Abstract

We revisit the study of prewetting transitions via Monte Carlo simulation for a single component fluid in contact with a planar solid surface. The principal focus of the present work is a more precise location of a prewetting transition by equating chemical potentials and surface tensions for the states of the adsorbed film in equilibrium at the prewetting transition. The surface tension is calculated from the pressure tensor and also from the Gibbs adsorption isotherm (for states below the prewetting transition in pressure). For the system studied by Finn and Monson [Phys. Rev. A 39, 6402 (1989)], a fluid interacting via a truncated Lennard-Jones 12-6 potential in contact with a 9-3 wall, the new calculations confirm the location of the prewetting transition in that study. We have also considered a similar system in which the fluid molecules interact with a shifted force Lennard-Jones potential. In this case layering transitions are observed in addition to prewetting, and apparently above the bulk triple point temperature. This confirms density functional theory predictions of layering transitions above the triple point temperature. The surface phase diagram also bears some similarity to that found in mean field studies of a lattice gas in contact with a 9-3 wall.