【摘要】 在杂化密度泛函理论的水平上研究了硝基苯氨 ( para nitroaniline pNA)分子的几何结构 ,并采用含时密度泛函理论 (TimeDependentDensityFunctionalTheory TDDFT)研究了 pNA分子的非线性光学性质。利用两态模型计算了pNA分子的一阶非线性光学超极化率 βz,并讨论了基矢效应和 βz 的色散关系。研究结果表明 ,对于该类分子 ,利用 6 - 31+ +G 基函数组可以得到收敛的结果。对于处于汽相的 pNA分子 ,计算得到的结果和最近的实验结果符合得很好。对于在较低的频率范围内 ,两态模型给出的 βz 的色散关系和实验结果符合得较好 ;在较高的频率范围内 ,还应考虑其它态的贡献更多还原

【Abstract】 The hybrid density functional theory is embraced to optimize the geometry of the para nitroaniline (pNA) molecule. Then time dependent density functional theory (TDDFT) is used to study the nonlinear optical properties of pNA molecule. The two state model is formulated to calculate the first order hyperpolarizabilty of pNA and the basis set effect is discussed. Numerical calculations show that the convergent results can be reached by 6-31++G * basis set for the molecule. The two state model can predict results of the first order hyperpolarizabilty which consist with experimental measurements in the lower energy range of the radiation field. However, for the higher energy of the radiation field, the dispersion of the first order hyperpolarizabilty given by the two state model doesn’t agree with experimental observation well, which indicates that the contribution of the other states should be considered and the solvent effect can not be neglected.更多还原