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 d escending 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 a t concave corners and kinks. On straight steps we find the process taking p lace on B-steps rather than on A-steps, with very similar Schwoebel barrier s 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 increas e 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 cel l sizes of today's ab initio calculations as compared to larger terraces. ( C) 2001 Elsevier Science B.V. All rights reserved.