The formation energies and the equilibrium concentration of vacancies, interstitial H, K, P, O and antisite structural defects with P and K in KH2PO4 crystals were investigated by ab initio total-energy calculations. The formation energy of interstitial H was calculated to be about 2.06 eV and it was suggested that it might be the predominant defect in KH2PO4 crystals. The formation energy of an O vacancy (5.25eV) was much higher than that of interstitial O (0.60eV). Optical absorption centres can be induced by defects of O vacancies, interstitial O and interstitial H. It was suggested that these defects may be responsible for the lowering of the damage threshold of the KH2PO4. A K vacancy defect may increase the ionic conductivity and therefore the laser-induced damage threshold decreases.

Formation Energies and Electronic Structures of Native Point Defects in Potassium Dihydrogen Phosphate. K.P.Wang, Y.Huang: Chinese Physics B, 2011, 20[7], 077401