Electronic structures of the oxygenated diamond (100) surfaces

By means of first principles method on the basis of density functional theory (DFT), the equilibrium geometries and density of states (DOS) of the two oxygenated diamond (100) surfaces, bridging model and on-top model are calculated. The results indicate that there are no surface states located in the band gap of the bridging model of oxygenated diamond (100) surface, and the occupied surface states in the valence band are attributed to the non-bonded O 2p orbital, O 2p and C 2p bonding orbitals, and C 2p and H ls bonding orbitals. By contrast, for the on-top model of oxygenated diamond (100) surface, the unoccupied surface states exist in the band gap, which originate from non-bonded C 2p and O 2p orbitals. In addition, the occupied surface states in the valence band are induced by non-bonded O 2p orbital and the C=O pi bond.