Prewetting transitions of Ar and Ne on alkali-metal surfaces

We have studied by means of density-functional calculations the wetting pro perties of Ar and Ne adsorbed on a plane whose adsorption properties simula te the Li and Na surfaces. We use reliable ab initio potentials to model th e gas-substrate interactions. Evidence for prewetting transitions is found for all the systems investigated and their wetting phase diagrams are calcu lated.