Comparison between some properties of small clusters and the (111) surfaceof palladium: a density-functional approach

We report a density-functional study of some electronic properties as well as the adsorption energy of atomic hydrogen and atomic oxygen on small pall adium clusters (n = 3-13). Concerning the bare clusters, we report the ioni zation potential and the estimated corresponding work function for the meta llic surface, as well as the cohesive energies and the mean Pd-Pd binding e nergy. The adsorption energies of H and O atoms are calculated, together wi th their influence on the work function and ionization potential. These the oretical results are compared with those from the literature; the calculate d surface properties (work function, adsorption energy, geometrical conform ation of the adsorbate), are in good agreement with available experimental data. On the other hand, cohesive energies of the clusters or Pd-Pd binding energies do not compare with available data for the bulk metal, showing th at the cluster approach is not valid in this case. (C) 2001 Elsevier Scienc e B.V. All rights reserved.