The MgO(110) surface and CO adsorption thereon. II. CO adsorption

The adsorption of a monolayer of CO molecules on the MgO (110) surface was studied at an ab initio level. The equilibrium position of the CO molecules above the surface and their bond lengths are optimised and compared for two possible cases: when the molecule is bound to the surface via its C or its O atom. The adsorption energies are found to be relatively small and very close to each other in the two cases (about 6.5 kcal mol^-1). The modifications caused by CO adsorption in the electronic charge distribution at the surface and in the density of states are analysed. The relaxation of the CO-saturated surface is found to be almost the same as that of the clean one (about 6.7% of the interplanar distance). The results obtained are compared with those for the (100) surface.