Structural and electronic properties of TiO2 polymorphs with effective on-site coulomb repulsion term: DFT+U approaches

Abstract

Abstract First-principles calculations using density functional theory (DFT) have been performed to investigate the structural and electronic properties of TiO2 polymorphs in rutile, anatase and brookite phases. The calculations based on local density approximation (LDA) and generalized gradient approximation (GGA) for Perdew-Burke-Ernzerhof (PBE) and Perdew-Burke-Ernzerhof for solids (PBEsol) were performed by considering the effect of Hubbard U correction in Ti 3d electrons of the TiO2. The DFT+U calculation improved the underestimated band gap which could solve the standard DFT problems. The best agreement of U values is found at U = 8.5 eV for rutile using LDA, U = 8.5 eV for anatase using GGA-PBEsol and U = 7.5 eV for brookite using GGA-PBEsol to improve the electronic band gap of TiO2 as a match with the experimental band gap