Cluster diffusion and island formation on fcc(111)metal surfaces

The role of cluster diffusion on Pt and Ir surfaces is discussed in the context of island nucleation on metals. By using molecular dynamics simulations based on a newly developed bond-order potential, the diffusion of Pt2 on a Pt(111) surface is studied. We observe that dimer diffusion proceeds via concerted motion on an hcp-bridge position towards the neighboring fcc-site. The importance of cluster diffusion is then investigated for the case of Ir island nucleation on Ir(111). We study the role of varying deposition rates on the island formation using an extended kinetic lattice Monte Carlo method that takes into account cluster diffusion and includes stacking fault positions. Our results reveal the strong influence of the deposition rate on island densities and shapes