Oxygen adsorption on the Ag(111) surface: a quantum chemical study by the NDDO/MC method

The forms of the atomic oxygen adsorbed on the Ag 111 face were investigated using the semi-empirical NDDOrMC . method within the modified cluster approximation. Two oxygen positions — surface over the octahedral hollow and the . . subsurface in the hollow one — between the first two layers of 111 face were studied. A cross-section of the potential energy for the oxygen penetration into subsurface positions has been computed. A new approach was applied to take into account the lattice relaxation caused by the interaction with adsorbate. The doubly-excited-CI-like correlation corrections to the diffusion and desorption barriers were estimated. The barrier of the oxygen atom diffusion through the surface was shown to be substantially lower than that of the desorption. q 2000 Elsevier Science B.V. All rights reserved.