Research on the neutral native point defects in KDP crystals using first-principles theory

The formation energies and concentrations at room temperature of various neutral native point defects in KDP crystals were studied using first-principles theory. The calculation results show that Hi may be the dominant point defect at room temperature in KDP. The formation energy of O vacancy (5.25 eV) is much higher than that of O interstitial (0.60 eV). Optical absorption center may be formed due to the O vacancy and may be responsible for the lowering of the damage threshold in KDP. K vacancy enlarges the volume of cavity surrounded by the eight O atoms by about 3.2%. K-vacacy(VK) defect may increase ionic conductivity and therefore laser-induced damage threshold decrease.