The remainder of this work describes the application of DC-DFT to polaron defects in oxide materials, where GGAs exhibit significant delocalization error. Periodic DFT is typically the method of choice for modeling solidstate materials, however that approach has failed to reproduce correct ground-state electronic and geometric structure in important cases, particularly with respect to the localized nature of O(2p)-derived holes obtained in doped silica and metal oxides. One such example is the polaron in Al-doped silica (SiO 2 ), where a Si 4+ ion is replaced by Al 3+ . Electron paramagnetic resonance (EPR) spectroscopy suggests that the unpaired spin is localized on a single oxygen atom adjacent to the defect center, creating a local structural distortion with a single elongated Al-O bond.