First-principle calculations of electronic structure and dielectric function of rutile TiO2 under hydrostatic pressure

Abstract The electronic structure and optical properties of rutile TiO2 under hydrostatic pressure are reported based on the first-principle calculations. The results indicate that both the lattice constants and the volume of TiO2 decrease with pressure increasing; however, the ratio of c/a is almost unchanged in such a case and the TiO6 octahedron in the unit cell transforms into regular octahedron at about 22.0 GPa. It is also shown that the band-gap of rutile TiO2 enlarge along two stages and the peak value of electronic states reduce with pressure, and these variations are found to be associated with the expansion of the O 2p and Ti 3d electronic states. Besides, we also calculated and analyzed the dielectric function of TiO2 under different hydrostatic pressure and the results indicate that the peaks in the imaginary part of dielectric function move to higher energy direction with pressure.