Resonant electron transfer between highly charged ions and metal surfaces: First-order vs. nonperturbative transition rates

Transition rates for resonant electron transfer between highly charged ions and metal surfaces are calculated within a simple first-order model and within the nonperturbative coupled-angular-mode (CAM) method. In the first-order model, image potentials are disregarded and hybridization effects are simulated by describing the ionic orbitals in terms of hydrogenic wave functions in the parabolic (Stark) representation. The CAM method employs a fairly realistic electronic potential that includes the classical image potentials. For typical cases, the deviations between first-order and CAM transition rates are such that the associated transition distances agree, on average, within one atomic unit. The reason for this agreement is indicated.