Microstructure and properties of anatase TiO_2 codoped with N and La

The crystal structures,electronic structures and optical properties of N or/and La doping anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory.The results showed that the octahedral dipole moments in TiO2 increase due to the changes in lattice parameters,bond length and charges on atoms,which was very effective for the separation of photoexcited electron-hole pairs and the improvement of the photocatalytic activity of TiO2.The narrowing band gap results in the red shift of optical absorption edges,and N+La codoped TiO2 manifested greater absorption in visible-light region.