Using the periodic density functional theory

the structures

formation energies

band structures and density of states were investigated with copper doped in TiO

2

adsorbed on the surface of (001) and (101)

substituted Ti sites of surface and subsurface

and in the vacancy of horizontal and longitudinal. The formation energy calculations suggested that Cu atom preferred to dope in the vacancy of the (001) surface

and the band-gap reduced obviously while the property of half-metal appeared. Analysis of the densities of states showed that the hybridization of Cu-3d and O-2p induced the appearing of CuO state

which was in good agreement with experimental result.