Local excitons in insulators and impurity doped metals

The local exciton spectra of some alkali-halide insulators and impurity doped lithium metal are calculated using atomic clusters to simulate the bulk solid. The calculations are ab initio and use unrestricted Hartree-Fock and second order many body perturbation techniques. Accurate results are obtained for sodium fluoride by incorporating these techniques into a simple Born-Haber type cycle that requires only free space atomic and ionic data to predict where the Na LI1,III edge exciton is located. Highly accurate results are obtained for lithium fluoride and a new interpretation of the soft x-ray region of that material is presented. The local absorption spectra of lithium metal doped with several divalent impurities are investigated. A theory explaining why several different impurity species exhibit the same spectrum in the dilute impurity limit is presented. The absorption spectra for various concentrations of magnesium and zinc in lithium metal are explained using a theory developed by Fano along with calculational results.U of I OnlyThesi