Theory studies on the linear and nonlinear optical properties of MnHg(SCN)4 crystal

The linear and nonlinear optical properties of MnHg(SCN)4 (MMTC) single crystal are studied by the Density Functional Theory (DFT) method. The optimized lattice constant can be compared with the experimental value. The DFT method is used to calculate the hyperpolarizability of MMTC single crystal and the second harmonic generation coefficient is studied by the ionic group theory. The obtained second harmonic generation coefficient is d15=17.14-25.91 pm/V, which is in agreement with the experimental result (19.8-28.8 pm/V). It is found that the greatest contribution for the second harmonic generation of MMTC crystal is from HgS4 anionic group.