Optical properties of Nb doped SrTiO3 from first principles study

The electronic and optical properties of Nb doped SrTiO3 are studied by ab initio linear muffin-tin orbital method in the atomic sphere approximation. The equilibrium lattice constants of SrTi1−xNbxO3 with x=0.0, 0.25 and 0.5 are found by minimization of the total energy curves. The computated lattice constants are in good agreement with experimental data. Our electronic band calculation shows that the Fermi level of SrTi1−xNbxO3 with x≥0.125 moves into the conduction bands and the system shows metallic behavior. The numerical results indicate that the Nb impurity atoms would lead to the distortion of the band edges. The complex dielectric function of SrTiO3 and Nb doped SrTiO3 are calculated using the random-phase approximation. The doping effect on the optical properties of SrTi1−xNbxO3 is discussed.