It was recalled that highly anomalous values, of the pre-exponential factor for atomic diffusion at surfaces, had been deduced from scanning tunnelling microscopy growth experiments. An extensive first-principles kinetic Monte Carlo study showed how long-range adsorbate interactions invalidated the standard nucleation-theory approach to the analysis of experimental island-density data. When adatom-adatom interactions were properly accounted for in the analysis of experimental data, the anomaly was removed. The deduced pre-factors were consistent with direct theoretical calculations. It was shown that the dependence of the island density upon the growth rate was modified by interactions. This could be used to identify adsorbate interactions in growth experiments.

Neglected Adsorbate Interactions behind Diffusion Prefactor Anomalies on Metals. S.Ovesson, A.Bogicevic, G.Wahnström, B.I.Lundqvist: Physical Review B, 2001, 64[12], 125423 (11pp)