Structure and generation mechanism of the peroxy-radical defect in amorphous silica

We provide a new model of the peroxy-radical defect in amorphous silica on the basis of quantum-chemical calculations applied to clusters of atoms to model the defect. In this model, the 29Si hyperfine splittings of the peroxy radical arise from a single silicon, in agreement with the previous experimental findings. Furthermore, we show that the present model of the peroxy radical is consistent with the diffusion-limited anneal mechanism of the E'gamma center, although our model of the E'gamma center is different from the conventional charged oxygen vacancy model.