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采用基于赝势平面波基组的密度泛函理论(DFT)方法,研究了有机晶体材料4-(4-二甲氨基苯乙烯基)甲基吡啶对甲苯磺酸盐(DAST)和4-(4-二甲氨基苯乙烯基)甲基吡啶2,4,6-三甲基苯磺酸盐(DSTMS)的电子结构和光学性质.结果表明,两种化合物具有相似的能带结构,其中价带顶和导带底分别含有较多二甲氨基和甲基吡啶中N原子的2p轨道成分.在线性光学性质方面,两种化合物具有较高的双折射率(Δn>0.5),在中远红外区均具有较好的透过性能.在二阶非线性光学性质方面,该类晶体具有较强的二阶倍频(SHG)效应,静态倍频系数d11约为150 pm V-1.由能带结构分析结果可知,体系的SHG效应与推拉电子基团之间的电荷转移密切相关,同时乙烯桥键在该电子转移过程中也起着重要作用.
(DFT) and 4- (4-dimethylaminostyryl) picolinic acid p-toluenesulfonate (DAST) were studied by means of density functional theory (DFT) -dimethylaminostyryl) picoline 2,4,6-trimethylbenzenesulfonate (DSTMS). The results show that the two compounds have similar band structure, in which the valence band The top and the bottom of the conduction band contain more 2p orbital elements, respectively, of the N atoms in the dimethylamino group and the picoline. In terms of the linear optical properties, the two compounds have higher birefringence (Δn> 0.5) All have good transmission performance.In the second-order nonlinear optical properties, the crystal has strong second-order multiplication (SHG) effect, the static multiplier d11 is about 150 pm V-1, The results of structural analysis show that the SHG effect of the system is closely related to the charge transfer between the electron-withdrawing groups and the vinyl bridge bond plays an important role in the electron transfer process.