He interaction with Xe and Kr adsorbed on graphite or Ag surfaces

We calculate the interaction V(r→) between a He atom and a system consisting of a Xe or Kr film adsorbed on either a graphite or a Ag surface. The dominant term in the energy is the sum of pair interactions U(r→-R${\to }_i$) with the adatoms; the choice of U(x) is based on gas-phase data. Other contributions arise from the substrate and from three-body interactions. The dependence on coverage is explored. There is also a small temperature dependence originating from the thermally excited adlayer motion. Agreement with bound-state resonance data for the graphite case is excellent. The potential functions should provide a reliable basis for scattering and thermodynamic calculations.