Multilayer relaxation of the Al(100) and Al(110) surfaces: an ab initio pseudopotential study

The multilayer relaxations of A1(100) and A1(110) surface are studied using the plane wave ah initio pseudopotential method within the local density f unctional theory. Our calculations show that the surface relaxation of A1(1 00) is an 'anomalous' outward relaxation, which is in excellent agreement w ith experimental results, although several previous empirical and semi-empi rical theoretical studies have predicted contractions that are contrary to the experiments. For the A1(110) surface, our calculations do show inward r elaxation, which is consistent with LEED experiments and other theoretical calculations. The origin of 'inward' and 'outward' relaxation is discussed. The surface energy is also studied in this work. (C) 2001 Elsevier Science B.V. All rights reserved.