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采用密度泛函理论(DFT)B3LYP和BhandHLYP方法,对6个不同金化合物[X-{Au(PMe3)}2]的几何结构、电子光谱以及极化率和三阶非线性光学(NLO)效应进行了计算分析.本文采用的计算方法和基组适合所研究的对象,并发现用PMe3代替PPh3对分子整体结构影响不大.另外,分子桥连部分的空间效应对极化率有明显影响,对三阶极化率影响却不大.关于6个分子的三阶NLO性质,由于X部分的电子性质及共轭程度不同,分子1a的三阶极化率γ值最小,分子2a的γ值最大.通过分析电子光谱和对应的分子轨道组成可知,Au在分子1a中做电子给体,而在分子2a～6a中做电子受体,表明Au在此类化合物中对NLO性质的贡献不同.
The geometrical structures, electronic spectra and polarizabilities of six different gold compounds [X- {Au (PMe3)} 2] and the third-order nonlinear optical (NLO) effects were investigated by density functional theory (DFT) B3LYP and BhandHLYP methods The calculation method and base set are suitable for the study, and found that PMe3 instead of PPh3 has little effect on the overall structure of the molecule.In addition, the spatial effect of the molecular bridging part has a significant impact on the polarization rate, Has little effect on the third-order polarizability.As for the third-order NLO properties of the six molecules, the third-order polarizability γ of the molecule 1a is the smallest due to the difference in the electronic properties and the degree of conjugation of the X moiety, and the γ value of the molecule 2a Maximum.Analysis of the electronic spectra and the corresponding molecular orbital composition shows that Au acts as an electron donor in molecule 1a and electron acceptors in molecules 2a to 6a show that Au contributes to the NLO properties in these compounds.