First-principles study on electronic states of SrWO4 crystals containing F-type color centers

The electronic structures of the SrWO₄ crystals containing F-type color centers are studied within the framework of the fully relativistic self-consistent Dirac–Slater theory using a numerically discrete variational (DV-X^α) method. The calculations indicate that either F or F⁺ center has donor energy level within the forbidden band. The electronic transition energies from the two donor levels to the bottom of the conduction band are 1.82 eV and 2.28 eV corresponding to the 685 nm and 545 nm absorption bands, respectively. It is, therefore, concluded that the 545–685 nm absorption bands are originated from the F and F⁺ center in SrWO₄ crystal respectively.