Calculations for the linear and nonlinear optical coefficients of ZCTC crystals

Abstract

AbstractThe structural, electronic, linear and nonlinear optical properties of ZnCd(SCN)4 (ZCTC) single crystal were studied by using quantum‐mechanical calculations based on the density functional theory (DFT) and pseudopotential method. The optimized lattice constant can be compared with the experimental values when the effects of temperature are considered. Combining with partial density of states of ZCTC crystal, it was found that C2p, N2p and S3p orbitals occur obvious hybrid, which is the main source of the second‐order nonlinear optical effect of ZCTC crystal. Then DFT has been used to calculate the hyperpolarizability of ZCTC single crystal, from which the second harmonic generation (SHG) coefficients was calculated using ionic group theory. The calculated SHG coefficients are d14 = 1.08 ∼ 1.93 pm/V and d15 = 4.01 ∼ 4.79 pm/V. Both of them are in agreement with the tendencies shown by the experimental results (d14 = 3.2 pm/V and d15 = 7.6 pm/V). It was also found that the greatest contribution for SHG of ZCTC crystal is from SCN anionic group.