The surface self-diffusion of a single adatom on a rhenium cluster with hexahedral structure was studied. The minimum energy paths and the corresponding energy barriers were determined by using the nudged elastic band method. The two diffusion mechanisms (direct hopping, exchange) for adatoms across the step edge were investigated. For adatom migration from a (00•1) facet to a neighboring (1¯1•1) facet, there were two paths, and the corresponding Ehrlich-Schwoebel barriers were so markedly high that the diffusion crossing of the step edge could not take place below 101K. Three diffusion paths for the adatom across the step edge between two neighboring (1¯1•1) facets were considered. It was found that the Ehrlich-Schwoebel barriers of these paths were high and that diffusion on (1¯1•1) facets occurred with difficulty below 261K. The calculated energy barrier for adatoms diffusing along the step edge was lower than that for adatoms on the (00•1) facet. The results showed that an adatom on the (00•1) facet should be trapped by the step edge, and then diffused along the step edge.

Surface Self-Diffusion of Re Adatom on the Re Cluster with Hexahedral Structure. Dai, X., Yang, J., Hu, W.: Physica B, 2013, 414, 97-102