First-Principle LDA+U and GGA+U Calculations on Structural and Electronic Properties of Wurtzite ZnO

Abstract

First-principles calculations with density functional theory (DFT) were carried out to explore the effects of Hubbard on-site Coulombic correction on the structural and electronic properties of wurtzite zinc oxide (ZnO). For an accurate prediction of ZnO properties, adequate Hubbard terms must be established due to changes in structural parameters produced by the correction of hybridization between Zn 3d and O 2p states. The calculations are based on the local density approximation (LDA) and the generalized gradient approximation (GGA) for Perdew-Burke-Ernzerhof (PBE) and Perdew-Burke-Ernzerhof for solids (PBEsol) were performed by applying Hubbard corrections U_d to Zn 3d states and U_p to O 2p states. The lattice parameters were closer to the experimental data and underestimated when Hubbard corrections U_d and U_p were applied in the calculation. The combination of the correction terms U_d and U_p managed to improve the underestimated bandgap of wurtzite ZnO, which might solve the standard DFT problems. The best Hubbard parameters U_d and U_p found for LDA+U at U_d = 6 eV and U_p = 8 eV, GGA-PBE at U_d =2 eV and U_p = 10 eV and GGA-PBEsol+U at U_d = 5 eV and U_p = 9 eV show a good agreement with the experimental bandgap.