Diffusion of nanoclusters on non-ideal surfaces

We use molecular-dynamics simulations to investigate the diffusion of nanoclusters on non-ideal surfaces, containing bond-length disorder, vacancy islands or monoatomic steps. We find that bond-length disorder does not affect diffusion significantly. When vacancy islands are present, it is found that the diffusion path avoids the neighborhood of these defects, which can be explained in terms of an effective repulsion between the defect and the cluster. Indeed, when a step is present, we find a barrier which opposes diffusion, analogous to the well-known Ehrlich-Schwoebel barrier for adatom diffusion. (C) 2003 Elsevier B.V. All rights reserved.