Extensive self-consistent real-space recursion-method calculations were performed for the Pt overlayer or the Pt, cluster on the Ni(ll1) surface and for hydrogen chemisorption on these systems. Correlations between the surface-atom local density of electronic-state properties before chemisorption, surface reactivity, and the initial-state contribution to the metal core-level shifts, respectively, is documented and discussed. The experimentally observed catalytic properties of Pt-Ni alloy surfaces are also briefly considered. o 1996 John Wiley & Sons, Inc.
one finds the family of Pt-Ni alloys with the fcc lattice. It is known that for any bulk Pt concentration the (111) surface is essentially enriched by platinum, forming a quasi-pure platinum overlayer if the bulk Pt content is about 50% or more 11-31. The subsurface layer is, on the contrary, enriched by Ni. The surface reactivity is strongly influenced by the alloying: The hydrogen-metal bond is reduced at the (111) face, especially for the cur for adsorption of CO and hydrocarbons [l,21. *Permanent address: PLAPIQUI (UNSCONICET), 12 de Pto.,Ni 0.5 stoichiometry 141; analogous effects oc-Octubre 1842,