Comparative first-principles analysis of the absorption spectra of ZnAl2S4 and ZnGa2O4 crystals doped with Cr3+
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan
Corresponding author: a email@example.com
Revised: 21 October 2005
Published online: 10 March 2006
Systematic first-principles analysis of the energy level schemes and ground state absorption spectra of trivalent chromium in ZnAl2S4 and ZnGa2O4 crystals has been performed in the present paper. The recently developed first-principles approach to the analysis of the absorption spectra of impurity ions in crystals based on the discrete variational multi-electron (DV-ME) method [K. Ogasawara et al., Phys. Rev. B 64, 115413 (2001)] was used in the calculations. The method is based on the numerical solution of the Dirac equation; no phenomenological parameters are used in the calculations. As a result, complete energy level schemes of the Cr3+ ion and its absorption spectra in both crystals were calculated, assigned and compared with experimental data. By performing analysis of the molecular orbital (MO) population, it was shown that the covalency of the chemical bonds between the Cr3+ and S2- ions is more significant than that one between the Cr3+ and O2- ions.
PACS: 71.15.Rf – Relativistic effects / 71.70.Ch – Crystal and ligand fields / 71.70.Ej – Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006