The positions of the interstitial O atoms in a PbWO4 crystal were simulated by computer. It was found that the formation energy of isolated point defects was low when interstitial O atoms existed around the W6+ ion. Based upon the computed results, the total density of states and the partial densities of states for perfect PbWO4 crystals and PbWO4 crystals containing interstitial O atoms were calculated by using the DV-Xα program. Upon analyzing the calculated results, it was concluded that an interstitial O atom could combine with 1 or 2 formal lattice O ions to form O molecular ions which caused the 350nm absorption band.

First-Principles Study of PbWO4 Crystal with Interstitial Oxygen Atoms. T.Chen, T.Y.Liu, Q.R.Zhang, F.F.Li, Z.J.Yi, D.S.Tian, X.Y.Zhang: Physica Status Solidi A, 2006, 204[3], 776-83