First-principles study on the electronic structures and absorption spectra for the PbWO4 crystal with lead vacancy

The electronic structures and absorption spectra for the perfect PbWO4 (PWO) crystal and the crystal containing lead vacancy VPb2− have been calculated using density functional theory code CASTEP with the lattice structure optimized. The calculated absorption spectra of the PWO crystal containing VPb2− exhibit seven absorption bands peaking at 1.72 eV (720 nm), 2.16 eV (570 nm), 2.81 eV (440 nm), 3.01 eV (410 nm), 3.36 eV (365 nm), 3.70 eV (335 nm) and 4.0 eV (310 nm), which are very close to the experimental values. It predicts that the 330, 360, 420, 500-750 nm absorption bands are related to the existence of VPb2− in the PWO crystal.