First principles study on point defect of Ba substituting for K in KDP crystals

The electronic structure and energy state density of Ba substituting for K in KDP crystals was studied by first principles calculations. The point defect narrows down the energy gap to about 6.3 eV, which corresponds to a two-photon absorption of 390 nm. This can explain the absorption of Ba-doped KDP crystals in ultraviolet(UV) region. Moreover, the defect only makes the surrounding crystal lattice and electronic structure slightly distorted, and thus little impact is placed on the overall structure of the crystal.