Structural and Electronic properties of Zinc Oxide (ZnO) using Density Functional Theory with Hubbard Correction

Abstract

In this thesis the structural and electronic properties of hexagonal wurtizite zinc oxide (ZnO) is investigated with density functional theory (DFT)+U using Quantum Espresso package. Our study is based on Density Functional Theory (DFT)+U with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional, Vanderbilt (ultra soft) pseudopotentials and the plane wave basis set implemented in the Quantum-ESPRESSO package. The calculation of the total minimum energy and the total minimum force of ZnO is calculated as a function of cutoff energy and Kpoints sampling. The total minimum energy per atom is decreasing with increasing cutoff energy due to variational principle. However, this trend can not be predicted from increasing the k-points sampling. Moreover, the equilibrium lattice constant is calculated using results obtained from energy convergence test (i.e., 50 Ryd and 7 × 7 × 7 ). The computational value of the equilibrium lattice constant is 6.06 °A. This result is in best agreement with experimental value which is 6.14 °A. Finally, discussing band structure and density of state of hexagonal wurtizite ZnO, the electrical property of hexagonal wurtizite ZnO is determined based on energy band gap.