A First-principles Study On Bulk CuO: Electronic Structures And Native Point Defects
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In this thesis, we have performed a first-principles study on strongly correlated monoclinic cupric oxide (CuO) by using the LSDA+U method implemented in the PAW method. Based on the optimized structural parameters, which are in good agreement with the experimental data, the electronic structure and the magnetic properties are obtained. Our calculations show that CuO is a semiconducting material with an indirect gap of about 1.0 eV. The semiconducting nature of CuO from our calculations is consistent with many experiments, but is qualitatively different from the LSDA calculations which incorrectly predict CuO to be metallic. The indirect gap of 1.0 eV is also in good agreement with many experimental results. We also found that in its ground state, CuO is antiferromagnetic with a local magnetic moment per formula of about 0.60 μB, which is close to the experimental values. By applying the LSDA+U method to a 2×3×2 supercell using the optimized structural parameters, we examine the structural relaxations, defect levels and defect formation energies of some possible native point defect in CuO. The results of the formation energies of the native point defects show that both in Cu-rich and O-rich environments, negatively charged Cu vacancies can be more easily formed in CuO than other native point defects. This explains why CuO is intrinsically a p-type semiconductor as measured by several experiments.