Interaction of atomic oxygen with copper clusters

Abstract

The chemisorption of atomic oxygen on Cu(001) is treated using a many-electron embedding theory in which the copper lattice is modeled as a 25-atom cluster. Of the three high symmetry sites investigated—fourfold, bridge, and atop-atom—the fourfold site is found to be most stable, with a dissociation energy of ∼6.1 eV (r⊥=0.7 Å), while the atop-atom configuration corresponds to the least stable site for atomic oxygen adsorption. The atop-atom site yields a radical-like state, ‘‘O−’’, whereas the open sites involve an oxide-like state, ‘O2−’, for oxygen. The principal valence ionization from oxygen is found to occur ∼8–10 eV below the vacuum level. The results of calculations on smaller clusters, CunO, n=2–5, are found to be in qualitative agreement with the results for Cu25O.