Electronic Properties of Cuprous-Chloride and Cuprous-Bromide
The first self-consistent all-electron energy band calculation of cuprous chloride using ab initio Hartree-Fock theory with nonlocal exchange is presented. Both polarization and relaxation corrections are included, and the resulting band structure is compared with the available optical data. Contrary to previous speculation, the band gap is found to be direct and equal to 5.1 eV. The influence of pressure is examined by repeating the calculation for lattice constants reduced to 99% and 95% of normal. These calculations show there is no reason to suspect that recent anomalies observed in CuCl are due to the pure material. Defects and impurities in CuCl are studied to determine the role they may play. Oxygen is found to be the most likely impurity to contribute to the observed anomalies. Calculations show it may pressure ionize to free charge carriers and thereby contribute to the high conductivity of the anomalous IIa phase in CuCl. Uniaxial stress is found to enhance this behavior of oxygen when compared to hydrostatic pressure. No simple explanation for the anomalous diamagnetism observed experimentally is found. Energy band calculations are preformed on cuprous bromide to determine its electronic structure and to see if trends present in cuprous chloride persist in the bromide. The effect of oxygen impurities in CuBr is also studied.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign