Adatom interlayer diffusion on Pt(111): an embedded atom method study

We use embedded atom method potentials to calculate the Schwoebel barriers for a large number of hopping and exchange processes of Pt and Ni adatoms descending steps of the Pt(I 1 1) surface. The barriers we find for hopping processes are too high to play any role in homo- and heteroepitaxy, but we find very low and even negative Schwoebel barriers for exchange processes at concave corners and kinks. On straight steps we find the process taking place on B-steps rather than on A-steps, with very similar Schwoebel barriers for Ni and Pt adatoms. We also find a strong dependence of the Schwoebel barrier on the lateral relaxation of step edges as caused by surface stress. For vicinal surfaces with high step density this effect causes an increase of the Schwoebel barrier if the width of the (I I I)-terraces is reduced. Due to the same effect, the barriers should be different for the small cell sizes of today's ab initio calculations as compared to larger terraces. (C) 2001 Elsevier Science B.V. All rights reserved.