Abstract: The lattice parameters, energy band structures, density of states and optical absorption spectra of N-doped, Nd-doped and Nd/N co-doped anatase TiO2 were calculated by the first-principles based on the density functional theory.The calculated results indicate that these three kinds of doping all induce lattice distortion for TiO2 with the biggest distortion of TiO6 octahedron after being doped by Nd,N doping introduces an impurity energy level above the maximum valence band and decreases the band gap of TiO2.Nd doping introduces empty band in the forbidden band of TiO2, which is mainly composed of Nd4f orbital.The experimental results for the red-shift of the absorption edge of TiO2 by the Nd doping can be explained perfectly from the decrease of the band gap.

Key words: The lattice parameters, energy band structures, density of states and optical absorption spectra of N-doped, Nd-doped and Nd/N co-doped anatase TiO2 were calculated by the first-principles based on the density functional theory.The calculated results indicate that these three kinds of doping all induce lattice distortion for TiO2 with the biggest distortion of TiO6 octahedron after being doped by Nd,N doping introduces an impurity energy level above the maximum valence band and decreases the band gap of TiO2.Nd doping introduces empty band in the forbidden band of TiO2, which is mainly composed of Nd4f orbital.The experimental results for the red-shift of the absorption edge of TiO2 by the Nd doping can be explained perfectly from the decrease of the band gap.