DYNAMIC CHARGE SUSCEPTIBILITY FOR THE INFINITE-U ANDERSON MODEL

The dynamic charge susceptibility for the single-impurity N-fold degen erate Anderson model is calculated within the noncrossing approximatio n. The calculations were done in all regimes: empty orbital, mixed val ent, and Kondo. At large N in the Kondo regime the results can be conn ected at low temperatures with the predictions of large-N mean-field t heory, suggesting a range of temperature where the validity of the two theories overlaps. Our smaller N results are presented in the context of electronic friction and energy transfer of an atom or molecule mov ing outside a metallic surface. It is suggested that some of the drama tic temperature and frequency dependences obtained should be relevant for this surface problem.