Study on structural and electronic properties of rutile TiO2 using DFT + U approach

Abstract

Effects of Hubbard parameters Ud, Up and Ud-Up pairs on structural and electronic properties of rutile TiO2 have been investigated using the DFT + U method, wherein Ud, Up were applied to Ti 3d-orbitals and O 2p-orbitals, respectively. The Ud, Up parameters range from 3 to 10 eV. Calculations have shown that Up = 10 eV is the optimal value to describe both structural and electronic properties of rutile. For Ud, an increasing in value of Ud results in expansion of band gap. However, high values of Ud lead to discrepancy in lattice constants. The effect of Ud is in good agreement with previous works. The obtained results also indicated advantages of combination of Ud and the optimal Up. The combination not only decreases discrepancy in lattice constants but also enlarges band gap more than Ud correction. Thanks to the optimal Up, we have achieved a band gap of 2.92 eV only with Ud = 7 eV. The Ud-Up pairs of 8-10, 9-10 and 10-10 give band gaps which is suitable with the experimental value.