Close-coupling calculations for ion-surface interactions

The time-dependent close-coupling equations for the ion-jellium-surface system are solved both by means of a fixed-ion self-energy formalism and by direct integration. The self-energies yield non-perturbative level shifts and widths, as well as information about the formation of hybrid orbitals in the combined potentials of ion and surface. Convergence of the self-energy results is achieved within a small set of discrete hydrogenic basis functions centered on the ion. In general, the calculated level shifts and widths are in good agreement with the results of other theoretical investigations. The direct time integration is applied in an exploratory study to the dynamics of hollow-atom formation in surface interactions of highly charged ions.