Surface diffusion of single Pt adatom on a Pt cluster with truncated octahedron structure was investigated via a combination of molecular dynamics and nudged elastic band methods. Using an embedded atom method to describe the atomic interactions, the minimum energy paths were determined and the energy barriers for adatom diffusion across and along step were evaluated. The diffusion of adatom crossing step edge between {111} and {100} facets had a surprisingly low barrier of 0.03eV, which was 0.12eV lower than the barrier for adatom diffusion from {111} to neighboring {111} facet. Owing to the small barrier to adatom diffusion across the step edge between {111} and {100} facets, the diffusion of adatoms along the step edge could not occur. The molecular dynamics simulations at low temperatures also supported these results. The results showed that mass transport would prefer steps with {100} micro-facets and the Pt clusters could have only {111} facets in epitaxial growth.

Surface Self-Diffusion of Adatom on Pt Cluster with Truncated Octahedron Structure. Yang, J., Hu, W., Chen, S.: Thin Solid Films, 2010, 518[14], 4041-5