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.
