Molecular dynamics simulations are used to calculate adsorption probabilities and diffusion coefficients of Xe on Pt(111) and Xe/Pt(111). Experimental trends are reproduced. The adsorption mechanism is found to be the modified Kisliuk model, with the addition of direct and indirect insertion in the Xe islands. Up to almost saturation coverage, adsorption via migration to island borders is the most important way of adsorbate assisted adsorption. Stimulated desorption is observed at high incidence energies.