Ab-initio study of transition-metal dimers on MgO(001) surfaces: Comparison of atomic and electronic properties

The adsorption properties of transition-metal (TM) dimers on defect-free MgO(001) surfaces were studied from a series of ab-initio electronic structure calculations for late TM atoms of Cu, Ag, Au, Ni, Pd, and Pt. Two dimer configurations were considered: an upright dimer structure and a flat lying dimer structure. For Cu, Ag, Au, and Pt, the upright dimer structure was found to be favored, and for Ni and Pt, the flat lying dimer structure. Also, for each dimer structure, the electronic structures of the TM dimers on MgO(001) were systematically examined. It was found that the electronic structures of the TM dimers depend on the adsorption structures and that their associated energy levels in the gap region of MgO significantly vary with the adsorption structures.