Oxygen adsorption on Ag(110): density functional theory band structure calculations and dynamical simulations

The adsorption of oxygen on silver surfaces is one of the crucial steps in the catalytic partial oxidation of ethene. From experiment it is known that O-2 physisorbs at low temperatures (T<40 K), whereas molecular and dissoci ative chemisorption is observed at higher temperatures. In this work, we pr esent the results of a theoretical study based on quasi-classical trajector y simulations of the scattering of an O-2 beam incident at the Ag(110) surf ace. The interaction of O-2 with the Ag surface was described by means of a London-Eyring-Polanyi-Sato model potential, which accounts for the electro nic charge transfer from the metal surface to the incoming O-2 molecule. Th is potential was built starting from the results of density functional theo ry band structure calculations obtained for the interaction of an oxygen at om with the high symmetry adsorption sites of the (110) surface. For the Ag -Ag interactions, both a harmonic Lennard-Jones potential and a many-body t ight-binding potential were used. The dependence of the molecular and disso ciative adsorption probability on the O-2 translational and internal energi es, on the incidence angles of the O-2 beam at the Ag surface, and the infl uence of the Ag surface temperature were investigated. (C) 1999 Elsevier Sc ience B.V. All rights reserved.