Defects and impurities GaAs ASGa ·Defect compositions→supercell 0●0 ● ● ● ●0 ·Neutral defects→charged defects ●Ga As No lattice optimization (fixed bulk volume), ●0 ● ●n but only the optimization of atomic positions ●) Frenkel Local atomic distortions (pair Local magnetic changes with defects 0Defects and impurities Co(A)  Defect compositions → supercell  Neutral defects → charged defects  No lattice optimization (fixed bulk volume), but only the optimization of atomic positions  Local atomic distortions  Local magnetic changes with defects