中文摘要：

采用密度泛函理论B3LYP／LanL2DZ／6—31＋G（d）方法，对实验合成的[Ni（dpedt）（dddt）]及以[-Ni（dpedt）（dddt）]为基础设计的系列衍生物的电子光谱和二阶非线性光学（NLO）效应进行计算分析．结果表明：配合物电子吸收光谱出现在近红外区，最强激发主要源于配体间的电荷转移（LLCT），并伴有一定的配体与金属间电荷转移（LMCT）．体系各分子的二阶NLO系数展βtot值较大，前线轨道能隙的大小影响体系的βtot值，能隙小则βtot值大，其中分子7βtot值最大．同时深层占据轨道与空轨道之间的电子跃迁对二阶NLO性质的贡献比较显著．

英文摘要：

Density functional theory B3LYP/LanL2DZ/6-31＋G（d） method was employed to optimize the structures of a series of organic molecules containing [Ni（dpedt）（dddt）]. Based on the obtained configuration, we calculated and analyzed the nonlinear optical （NLO） properties and electric spectra of these molecules. Results show that the calculated electronic absorption spectra of the coordination complex exhibit in NIR region. The calculated electronic absorption spectra of the organic molecules exhibits LLCT and LMCT. The static total second-order polarizabilities （βtot） of the series of organic molecules were found to be related to the energy gap of the frontier molecular orbital. The molecule with smaller energy gap of the frontier molecular orbital shows larger βtot value. In addition, the mole- cule 7 shows the largest βtot value. Finally, the charge transfer transitions from deeper occupied molec- ular orbital to the unoccupied molecular orbital obviously contributed to second-order NLO coeffi- cients.