Linear and non-linear optical properties of AgBO3(B=Nb, Ta): First principle study

The linear and nonlinear optical properties of ferroelectrics AgBO₃ (B=Ta, Nb) are studied by density functional theory (DFT) in the local density approximation (LDA) expressions based on first principle calculations without the scissor approximation. Specially, we present calculations of the frequency-dependent complex dielectric function ε(ω), and the second harmonic generation response coefficient χ⁽²⁾(-2ω,ω,ω) over a large frequency range in rhombohedral phase for the first time. The electronic linear electrooptic susceptibility χ⁽²⁾(-ω,ω,0) is also evaluated below the band gap. These results are based on a series of the LDA calculation using DFT.