First-principles investigation of the surface structures of Cu(n, n-1, 0) (n=2, 3 and 4) stepped surfaces

Multilayer relaxation at high-index Cu(n, n-1, 0) (n=2, 3 and 4) stepped surfaces was determined by the first-principles pseudopotential plane wave (PPPW) method. For those surfaces that have n and n-1 atom-rows in terrace and subterrace, respectively, the topmost 2n-2 interlayer spacings contract, while the 2n-1st interlayer spacing expands. There is no similar rule found for the relaxations parallel to the surfaces. Compared with the bulk terminated structure, a thin compact layer, which consisted of the topmost 2n-1 atom layers and separated slightly from the underneath atom layers, makes the surface more flat after relaxation. The bond-lengths between the step edge (first layer) atom and its nearest-neighbors do not depend on the surface termination, but only on the local coordination. (C) 2010 Elsevier Ltd. All rights reserved.