Ab initio cluster calculations on point defects in amorphous SiO2

Recently, there have been considerable advances in quantum-chemical calculations on clusters of atoms designed to model local defect centers in amorphous materials. In particular, this review attempts to put into perspective the recent calculated results of the point defects in pure and doped a-SiO2, which have attracted renewed attention in view of fabrication of Bragg gratings in optical fibers and waveguides. Recent sophisticated calculations may challenge the conventional models of several defect centers in a-SiO2.