Investigating the naturally occurring forms of TiO₂ on electronic and optical properties using OLCAO-MGGA-TBO9: a hybrid DFT study

Abstract

In this paper, a detailed study and analysis on the electronic and optical properties of anatase, rutile and brookite titanium dioxide (TiO2) which are the naturally occurring phases of TiO2 have been carried out. We have obtained these properties using the self-consistent orthogonalized linear combination of atomic orbitals with meta-generalized gradient approximation (MGGA) and Tran and Blaha (TBO9) as exchange–correlation under the framework of density functional theory. Obtained results on band gap value (E g), dielectric constant and refractive index as calculated by considering the optimal value of c (system-dependent parameter) have been analyzed statistically and are found to be much closer to the experimental values and are better than the other approaches published in the literature. It is seen that optical absorption for all the three phases of TiO2 occurs in UV region of EM spectrum. Using statistical analysis in correlation with other effective methods such as mBJ, GGA + U, GGA + Ud + Up, LSD + U, GW and HSE06 functional, it is found that MGGA-TB09 gives a better description of electronic structure and optical properties with less computation time. This work provides good understanding of electronic and optical properties of TiO2, stems a foundation for its possible applications in photo catalytic activities of dye sensitized solar cells.

Theoretical investigation on un-doped and doped TiO2 for solar cell application

“…The integration over the entire Brillouin zone of momentum matrix elements between occupied and unoccupied wave functions gives the direct interband share in the dielectric functions imaginary part (ε 2 (ω)). ε 2 (ω) is evaluated using the equations given in [64].…”

DFT based studies on the structural, electronic and optical properties of LiNbO3 using some hybrid techniques

“…From the obtained results, it implies that the dielectric function is square of the refractive index for both approaches. η(ω) and k(ω) both are related in terms of dielectric constant as represented by Kramers-Kronig [25].…”

“…Authors in [23] present DFT and DFT+U based calculations along with GGA and Heyd-Scuseria-Ernzerhof hybrid functional (HSE06) and found that stoichiometric LiNbO3 with HSE06 hybrid exchange-correlation functional widens the fundamental band gap concerning PBEsol at the cost of increased simulation time. Very recently, in our previous works [24][25][26][27][28], we have adopted OLCAO schemes in combination with PBES and TB09 to verify distinct phases of TiO 2 and recognized that outcomes are an approximation of experimental data. Evaluated data of Strontium Sulphide (SrS) by MGGA are the best match of experimental data while underestimation is induced by GGA and LDA [29].…”

TiN Bridged All‐Solid Z‐Scheme CNNS/TiN/TiO2−x Heterojunction by a Facile In Situ Reduction Strategy for Enhanced Photocatalytic Hydrogen Evolution

“…In other words, the conduction band of TiO 2 is mainly composed of Ti 3d orbitals. [ 17,18 ] As for CN, N 2p orbitals play a decisive role in the formation of the valence band. The conduction band is principally composed of C 2p orbitals.…”