First-principles study of Pd-V surface alloys II. Chemical reactivity

Impurities in transiton metal surfaces are known to modify the chemical reactivity of those surfaces. We have previously shown that vanadium in and under Pd(111) surfaces alters the electronic structure of the surface atoms considerably [R. Hirschl and J. Hafner, Surf. Sci. 498 (2002), preceding article]. In this work we investigate the changes in the chemical properties of Pd(111) surfaces after alloying with submonolayer amounts of V using CO as a test adsorbate. We have performed ab initio density functional theory calculations based on a plane wave basis set and projector augmented wave pseudopotentials. The influence of using two different exchange-correlation functionals is studied. We investigate the local adsorption energies and geometries on different alloy surfaces as compared to the pure Pd surface, followed by a detailed analysis of the local and partial density of states of the surface and adsorbate atoms and their electronic interaction. Local adsorption properties can be understood in terms of the changes in the d-band structure through alloying. Our results are discussed in the context of experiments and investigations of other binary transition metal surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.