Stable structure and optical properties of fused silica with NBOHC- E ′ defect

First-principles method is used to simulate the stable structure and optical properties of a 96-atom fused silica. The preferable structure of NBOHC- E ′ (non-bridging oxygen hole center (NBOHC) and E ′ center) pair defect is predicted to be located at 2.4 Å for the Si–O bond length. The quasi-particle G0W0 calculations are performed and an accurate band gap is obtained in order to calculate the optical absorption properties. With the stretching of the Si1–O1 bond, an obvious redshift can be observed in the absorption spectrum. In the case of NBOHC- E ′ pair, the p-orbital DOS of Si1 atom will shift to the conduction band. Two obvious absorption peaks can be observed in the absorption spectrum. The calculation reproduced the peak positions of the well-known optical absorption bands. (paper)