The adsorption of Ar on substrates of Li is investigated within the framework of a density functional theory which includes an effective pair potential recently proposed. This approach yields good results for the surface tension of the liquid-vapor interface. The behavior of the adsorbate in the cases of a single planar wall and a slit geometry is analyzed as a function of temperature. Asymmetric density profiles are found for fluid confined in a slit built up of two identical planar walls leading to the spontaneous symmetry breaking (SSB) effect. We found that the asymmetric solutions occur even above the wetting temperature in a range of average densities , which diminishes with increasing temperatures until its disappearance at the critical prewetting point . In this way a correlation between the disappearance of the SSB effect and the end of prewetting lines observed in the adsorption on a one-wall planar substrate is established. In addition, it is shown that a value for can be precisely determined by analyzing the asymmetry coefficients.

Received: 17 June 2009, Accepted: 28 August 2009; Edited by: S. A. Cannas; DOI: 10.4279/PIP.010001