香草醛晶体光学非线性系数的有限场方法研究

Studies on the Nonlinear Optical Crystal of Vanillin Using Finite Field Method

采用有限场方法计算了有机非线性材料3-甲氧基-4-羟基-苯甲醛(分子式C_8H_8O_3,简称MHBA)的二阶非线性光学系数d_(21),d_(22),d_(23),d_(25_).研究结果表明在MP2近似和6-31G+(p,d)基组水平上理论值能较好地与实验值符合,同时也表明拉电子基团HC(?)O和推电子基因HO对于MHBA分子的光学非线性性能的影响很大,而晶体中分子间的氢键作用对d值的贡献很小.

The second - order optical nonlinearity of crystal 3 - methoxy - 4 - hydroxy - benzaldehyde (MHBA) was studied by using the finite field method at the MP2 level with basis set of 6-31G+ (p,d). The theoretical results of d21, d22, d23 and d25 were in agreement with the experimental data. The eletron -accepting group HC = 0 and the electron - donating group HO played important roles in the nonlinear optical property of MHBA. The results also showed that the hydrogen bonds did not contribute signifcantly to the crystal nonlinear optical coefficients.