First principle studies on the electronic structures and absorption spectra under polarized light for the PbWO4 crystal with oxygen vacancy

The electronic structures and absorption spectra for the perfect PbWO4 (PWO) crystal and the PWO crystal containing oxygen vacancy VO2+ have been studied by using full-potential (linearized) augmented plane-wave (LAPW)-bar +-bar local orbits (lo) method with the lattice structure optimized. The calculated results indicate that the optical properties of the two types of PWO crystals are anisotropy and their optical symmetries correspond to their lattice structure geometries, respectively. The perfect PWO crystal has no absorption spectrum in the energy region of visible light. However, for the PWO crystal containing VO2+, there occurs an additional absorption spectrum in this region, which can be fit into two Gaussian-shape absorption spectra with peaks at 370 and 420 nm. These peaks are located at the experimentally observed position. As a conclusion, the 350 and 420 nm absorption spectra are related to the existence of VO2+ in the PWO crystal