Wetting and thick-thin film transitions in a model of argon at a solid CO2substrate

Abstract

Using a simple free-energy functional, we have determined the location of the transition from partial to complete wetting and the thick-thin-film transition line for a model of gaseous argon at a solid carbon dioxide substrate. The wetting transition temperature is significantly higher than that calculated by Ebner and Saam for the same model and the thick-thin transition line lies much closer to the bulk gas-liquid coexistence curve. Our results suggest that thick-film formation will only occur for high temperatures and this is why such films have not been observed in computer simulations and in other recent studies of this model. We show that long-ranged transverse (parallel to the surface) pairwise correlations occur at the edge of the thick and thin films which coexist on the transition line. The range of these correlations becomes infinite at the surface critical temperature and, for the thick film, at the wetting transition temperature.