First-principles calculations were performed which were based upon spin-polarized density-functional theory for the adsorption and diffusion of Au, Ag and Pb atoms on NaCl(001), KCl(001) and KBr(001) surfaces. The influence of adatom charge upon adsorption and diffusion was also considered. In order to characterize the various systems, charge transfer between surface and adatom was explicitly calculated and the relative stability of the various charge states was considered. The results showed that in general, apart from positively charged systems, the adatoms were weakly bound to the surface via orbital polarization and ionic interactions, and relatively little charge transfer occurred. The Au and Ag adatoms were highly mobile on all surfaces, although they could be pinned by removal of an electron. In contrast, Pb adatoms were fairly immobile, and their mobility increased upon charging. Analysis of the charge stability suggested that Ag offered the possibility of charge-controlled mobility on insulators.

First-Principles Study of Adsorption, Diffusion, and Charge Stability of Metal Adatoms on Alkali Halide Surfaces. M.H.Hakala, O.H.Pakarinen, A.S.Foster: Physical Review B, 2008, 78[4], 045418 (8pp)