DENSITY-FUNCTIONAL STUDY OF ATOMIC NITROGEN AND OXYGEN-CHEMISORPTION ON MODEL CLUSTERS SIMULATING THE CU(100) AND AG(100) SURFACES

Density functional calculations which explicitly use the density gradi ent type nonlocal corrections to exchange and correlation are reported for the adsorption of atomic nitrogen and oxygen on the four-fold sit es of (100) copper and silver surfaces simulated by Cu-5 and Ag-5 clus ters. Binding energies, equilibrium distances and harmonic vibrational frequencies are in good agreement with the available experimental and high level theoretical data. An ionic contribution is found in the bo nds between N and O and Cu and Ag clusters. Metal d orbitals are invol ved in the covalent part of the bond.