The first-, second- and third-order nonlinear optical properties of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole in gas phase employing sum-over-states (SOS) method have been calculated for the first time. The ground state molecular structure of N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole was obtained by the geometrical optimizations based on the B3LYP/6-31[Formula: see text]G(d) level. The energy of excited states and transition dipole moments between different excited states were obtained by using the time-dependent density functional theory (TDDFT) based on the CAM-B3LYP/Sadlej POL level. Charge transfer during electron excitation was analyzed based on hole and electron distributions. Our calculations showed that the N-(6-hydroxyhexyl)-5-nitroazophenyl carbazole has good nonlinear optical properties and its nonlinear optical properties arise from charge-transfer excitation and local excitation but charge transfer plays the leading role.

中文翻译：

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N-(6-羟基己基)-5-硝基偶氮苯基咔唑非线性光学性质的理论研究

首次采用状态总和(SOS)方法计算了N-(6-羟基己基)-5-硝基偶氮苯咔唑在气相中的一阶、二阶和三阶非线性光学性质。N-(6-羟基己基)-5-硝基偶氮苯基咔唑的基态分子结构是通过基于B3LYP/6-31[公式：见正文]G(d)能级的几何优化得到的。利用基于CAM-B3LYP/Sadlej POL能级的时间相关密度泛函理论(TDDFT)获得了激发态的能量和不同激发态之间的跃迁偶极矩。基于空穴和电子分布分析电子激发期间的电荷转移。