Specific features in the band structure and linear and nonlinear optical susceptibilities of La₂CaB₁₀O₁₉ crystals

The electronic and optical properties have been calculated for monoclinic La₂CaB₁₀O₁₉ (LCB) crystal using the state-of-the-art full potential linear augmented plane wave method. We present results for the band structure, density of states, birefringence, imaginary and real parts of the frequency dependent linear and nonlinear optical response. We have found that LCB is a semiconductor with an indirect energy band gap of about 4.45 eV. A simple scissor operator is applied to adjust the band energy gap from the calculations to match the experimental value (5.4 eV). The calculated birefringence of the LCB crystal has positive sign in agreement with the experimental data. Calculations are reported for the frequency-dependent complex second-order nonlinear optical susceptibilities χ_abc⁽²⁾(ω) up to 6 eV and for zero-frequency limit χ²(0). LCB exhibits second harmonic generation efficiency about two times larger than KDP crystal (KH₂PO₄).