First-principles study on the electronic structure of CaWO 4 crystals containing the F-type centers

Abstract

The electronic structure of CaWO 4 crystals containing the F-type color centers are studied within the framework of the fully relativistic self-consistent Dirac–Slater theory, using a numerically discrete variational ( D V - X α ) method. The results indicate that the F and F + centers reveal donor energy levels in the forbidden gap. The optical transition energies are 1.89 eV and 2.42 eV (660 nm and 515 nm, respectively). We conclude that the experimentally observed 520 nm absorption band could originate from the F + center.