AB-INITIO RESULTS FOR THE ADIABATIC ATOM-SURFACE INTERACTION FOR HELIUM AND NEON ON A SIMPLE METAL

We report an ab initio calculation of the adiabatic electronic propert ies of He and Ne atoms interacting with a jellium (Al-like) surface, i n the framework of the embedding method and using density functional t heory in the local density approximation. In particular, attention is focused on the repulsive atom-surface potential. For incident atoms wi th initial kinetic energies in the typical experimental range (up to a bout 200 meV), it is shown that Ne gets closer to the metal than He. T his is in agreement with the experimental observation of a greater sen sitivity to the surface electronic structure of Ne than of He, but in contrast with results obtained by simply applying the effective medium theory to the Ne/metal system.