Electronic and optical properties of three phases of titanium dioxide: Rutile, anatase, and brookite

Using the self-consistent orthogonalized linear-combination-of-atomic-orbitals method in the local-density approximation, the electronic structure and the optical properties of three phases of titanium dioxide have been studied. For rutile, the calculated band structure, equilibrium lattice constant, and bulk modulus are in good agreement with other recent calculations and with experimental data. The results on the ground-state properties of anatase and brookite are reported. Compared with the rutile phase, anatase has similar ground-state properties except for a larger band gap, whereas brookite has relatively smaller bulk modulus. The optical properties of these three phases are also calculated using the band-structure results and compared with the available measurements. For the rutile phase, the anisotropic properties of the dielectric function are in good agreement with the reflectance spectroscopy. For the anatase phase, there are very limited experimental optical data for comparison. For the brookite phase, no experimental data are available. Our calculations show subtle differences in the optical properties of these three phases.