First-principles study on electronic structures and color centers in BaWO4 crystal with barium vacancy

The electronic structures and absorption spectra for the perfect BaWO4 (BWO) crystal and the BWO crystal containing barium vacancy (VBa2-) have been studied by using density functional theory code CASTEP with the lattice structure optimized. For the BWO crystal containing VBa2-, there exhibit four absorption bands peaking at 0.71 eV (1751 nm), 1.85 eV (672 nm), 3.43 eV (362 nm) and 3.85 eV (322 nm), respectively. The origins of the absorption bands have been discussed and corresponding color centers also have been established.