Strong Coulomb correlation effects in ZnO |
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Authors: | SZh Karazhanov P Ravindran U Grossner H Fjellvåg |
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Institution: | a Centre for Material Science and Nanotechnology, Department of Chemistry, University of Oslo, PO Box 1033, Blindern, N-0315 Oslo, Norway b Physical-Technical Institute, 2B Mavlyanov St., Tashkent 700084, Uzbekistan c Department of Physics, University of Oslo, PO Box 1048, Blindern, N-0316 Oslo, Norway |
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Abstract: | The electronic structure, band parameters, and optical spectra of wurtzite-type ZnO were studied by first-principles calculations within different approximations of the density functional theory. The local-density approximation underestimates the band gap, the energy levels of the Zn-3d states, the band dispersion, the crystal-field splitting, the spin-orbit interaction, and location of peaks in the optical spectra. The generalized-gradient approximation slightly corrects the discrepancies with the experimental findings and it shows good agreement for the optical spectra with experimental data at energies 10-20 eV for E⊥c. Studies within the local-density approximation with the multiorbital mean-field Hubbard potential show that strong Coulomb correlations are in operation. From effective mass calculations it is found that holes are much heavier and more anisotropic than the conduction-band electrons in ZnO. |
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Keywords: | 71 15 -m 71 22 +i |
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