The nonlinear optical susceptibility and electro-optic tensor of ferroelectrics: first-principle study

摘要

The nonlinear optical properties of some ABO_3 materials (BaTiO_3, KNbO_3, LiTaO_3 and LiNbO_3) are studied by density functional theory (DFT) in the local density approximation (LDA) expressions based on firstprinciple calculations. Our goals are to give the details of the calculations for linear and nonlinear optical properties, including the linear electro-optic (EO) tensor for some ABO_3 structures with oxygen octahedral structures using first-principles methods. These results can then be used in the study of the physics of ferroelectrics, specifically, we present calculations of the second harmonic generation response coefficient X_(ijk)~(2)(-2ω,ω,ω) over a large frequency range for ABO3 crystals. The electronic linear EO susceptibility X_(ijk)~(2)(-ω,ω, 0) is also evaluated below the band gap. These results are based on a series of the LDA calculations using DFT. Results for X_(ijk)~(2)(-ω,ω,0) are in agreement with experiments below the band gap. The results are compared with the theoretical calculations and the available experimental data.