Surface embedded-atom method potentials were used to investigate the energy landscape of vacancies which diffused over, along and near to steps on the low-index faces. The vacancy diffusion barriers were compared with those for adatoms. Barriers to vacancies which diffused on the surfaces of terraces near and up close-packed step-edges were calculated for the (111), (100) and (110) surfaces. Large (>0.2eV) Ehrlich-Schwoebel barriers to vacancies ascending step-edges occurred on all 3 faces, and these barriers were enhanced with respect to those for adatoms. Barriers to their diffusion along step-edges, and around the kinks and corners of vacancy islands, were calculated for the (100) surface. A high (0.148eV) vacancy corner-type Ehrlich-Schwoebel barrier occurred here. The so-called kink Ehrlich-Schwoebel barrier, which involved an exchange mechanism, was very small (0.007eV). An accurate scheme was developed for estimating the vacancy energy landscape in terms of bond-breaking and atomic coordinations at the relevant surface lattice sites. The role played by vacancy diffusion barriers in the structure of 2-dimensional vacancy islands and 3-dimensional vacancy pits on (100) was assessed. The vacancy Ehrlich-Schwoebel effect promoted a pitted morphology which persisted at above room temperature. The calculated vacancy diffusion barriers did not support the suggestion that vacancy diffusion on top of clusters could help to account for the behavior of observed scaling exponents for the coarsening or diffusion of Ag clusters on (100)Ag.

Ehrlich-Schwoebel Effect for Vacancies - Low-Index Faces of Silver. M.I.Haftel: Physical Review B, 2001, 64[12], 125415 (9pp)