Theoretical analysis of thermally stable adsorption forms of oxygen on silver

Abstract

Theoretical analysis of the properties of oxygen in the surface layer of silver is performed in a cluster approximation. The oxygen molecule is placed in an octahedral cavity of the Ag14 cubic cluster. The O2/Ag14 system is optimized and structural parameters determined by the ab initio Hartree- Fock method. The energies are estimated by methods taking into account electron correlation in the Moller- Plesset and density functional theory approximations. For the three nonequivalent positions of O2 in the Ag14 cluster,it is shown that the molecular forms of oxygen may be stabilized. The calculations showed that the ground state of the O2/Ag14 system is a triplet but the spin density is delocalized over the silver atoms. Spin polarization leads to splitting of the 3Σg- level. The oxygen molecule has intermediate parameters between the superoxide O 2 1− and peroxide O 2 2− with the bond length R(O- O) 1.41 a.