Model of diffusion on deformable lattices. III. Adatom-interaction effects

Abstract

We present results of theoretical studies of diffusion in a lattice-gas model of a deformable lattice, which has been proposed to explain the anomalous diffusion anisotropy of H adatoms on a W(110) surface. In this work, we consider the effects of finite adatom-adatom interactions to diffusion in the model. In particular, using Monte Carlo simulation methods we study the properties of both tracer and collective diffusion in the presence of various spatially ordered phases within a model phase diagram of H/W(110). To incorporate the role of the energy barriers associated with diffusion more realistically, we select carefully a choice for transition probabilities used within the Monte Carlo method. We demonstrate that while the tracer and collective diffusion tensors behave in a fundamentally different manner within the model, the corresponding diffusion anisotropies are similar and are mainly controlled by the symmetry of the adlayer phase.