Several features of nonlinear optical susceptibilities of LiGaX2 (XÂ =Â S, Se) ternary compounds

We report theoretical calculation of the linear and nonlinear optical susceptibilities based on one of the most accurate methods for the computation of the linear and nonlinear optical susceptibilities of solids within density functional theory (DFT). The linear optical properties show negative uniaxial anisotropy indicating the strong anisotropy. Our calculations show that these crystals possess negative birefringence. The negative uniaxial anisotropy and birefringence will be in the favor of our calculated χijk(2)(ω). These crystals possess very high first-order in the infrared spectral region.