Study on structural and electronic properties of rutile TiO 2 using DFT  + U approach

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