Molybdenum Clusters on a TiO2(110)Substrate Studied by Density Functional Theory

摘要

A theoretical study on molybdenum clusters adsorbed on a rutile TiO2(110)substrate is reported.Using density functional theory,equilibrium geometries,atomic charges,and total energies have been calculated for clusters containing up to five Mo atoms.Isolated Mo adatoms are strongly oxidized and repel each other.The Mo oxidation state is considerably lowered as soon as the first short Mo-Mo bond is formed.The relative stability of different cluster geometries can be understood from the competition between Mo-Mo and Mo-O bonding.Some low-energy structures for two and three Mo atoms involve large displacements of a substrate oxygen atom.The most stable five-atom cluster,a square-based pyramid,is identified as the nucleus of epitaxial growth of bodgmma-centered cubic molybdenum films on TiO2(110).