取代位置对香豆素衍生物二阶非线性光学性质影响的DFT研究

采用密度泛函理论（DFT）B3LYP/6-31G方法，对设计的6个不同位置取代氨基的香豆素衍生物的几何构型进行优化。在所得优化结构的基础上对这些分子的稳态二阶NLO系数β值进行计算分析，并采用含时密度泛函理论（TD-DFT）方法计算了其电子性质，研究了取代位置对香豆素类衍生物分子的二阶NLO性质的影响规律。结果表明：当氨基取代在4号位时香豆素分子中的羰基表现出供电性，对分子内电荷转移非常不利，不利于提高分子的β值；当氨基取代在在3、5、6、7、8位时分子中的羰基表现出吸电性，使分子形成D-π-A构型，并且氨基在3、7位的取代能够扩大体系的共轭范围，有效增加了香豆素分子的βtot值。

Investigation on effects of substitution position of coumarin on the second-order nonlinear optical properties by DFT method

The density functional theory (DFT) B3LYP method based on the 6-31G level was employed to optimize the geometric structures of six amino coumarin derivatives. On the basis of obtaining stable molecular configuration, combined with time-dependent density functional theory (TD-DFT), the static second-order nonlinear optic polarizabilities (β) and the molecular electric spectrum were calculated by the same method. The results indicated that when amino substitute at the fourth position of coumarin the carbonyl show electron donating property which is a disadvantage for intramolecular charge transfer. When amino substitute at the third, fifth, sixth, seventh and eighth position of coumarin the carbonyl show electron with drawing property which makes the molecule form D-π-A configuration. And the third and seventh position can expand the conjugate system of molecule which can increase the βtot value of coumarin effectively.