Structural, electronic and optical properties of brookite phase titanium dioxide

Structural, electronic and optical properties of titanium dioxide (TiO2) in brookite phase were studied via first-principles calculations in the framework of density functional theory (DFT). The exchange-correlation functional from local density approximation (LDA) and generalized gradient approximation (GGA) were used to calculate the properties of brookite TiO2. The structural parameters of brookite in orthorhombic structure (Pbca space group) are in good agreement with the previous theoretical and experimental data. The obtained direct band gaps from GGA are slightly higher than LDA. Both LDA and GGA band gaps underestimate the experimental band gap due to the well-known limitation of DFT. The density of states (DOS) displays the hybridization of O 2p and Ti 3d states and Mulliken population analysis presents the net charge of Ti and O atoms in brookite. The dielectric function was also analyzed together with other optical properties such as refractive index, reflectivity, loss function and absorption coefficient. The first-principles calculations on the least studied TiO2 in brookite phase using different exchange-correlation functional from LDA and GGA provide theoretical understanding about its structural, electronic and optical properties. Besides, these results would give a better support for technological applications concerning TiO2 materials using brookite phase.