In this paper, polyvinyl carbazole fragments with side-hung chromogenic groups were used as the parent. The relationship between the structure and the properties of NLO was studied by changing the type of spacer groups on chromogenic groups with density functional theory (DFT). The results show that all designed systems have significant second-order NLO response. The first hyperpolarizability ( β 0 ) of the system has the following regularity (taking PBE0 algorithm as an example): the β 0 value of the system is related to the type of electron-donating and electron-withdrawing spacer group (X).The β 0 value of electron-donating spacer group is larger than that of electron-withdrawing spacer, and the β 0 value of the molecule is independent of the size of the spacer group. When the spacer group is methyl, the value of β 0 (168.1 × 10 −30 esu) is the largest in tested electron-donating group. When the spacer group is an electron-withdrawing group, the value of β 0 is related to electron-withdrawing ability, and the value of β 0 is inversely proportional to the electron-withdrawing ability of the spacer group.

中文翻译：

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间隔基团对聚乙烯咔唑分子片段非线性光学性质影响的理论研究

在本文中，具有侧悬显色基团的聚乙烯咔唑片段被用作母体。利用密度泛函理论(DFT)，通过改变显色基团上的间隔基团的类型，研究了NLO的结构与性质之间的关系。结果表明，所有设计的系统都具有显着的二阶 NLO 响应。系统的第一超极化率（ β 0 ）具有以下规律（以PBE0算法为例）：系统的β 0 值与给电子和吸电子间隔基（X）的类型有关。给电子间隔基的β 0 值大于吸电子间隔基的β 0 值，且分子的β 0 值与间隔基的大小无关。当间隔基团为甲基时，β 0 (168. 1 × 10 -30 esu) 是测试的给电子基团中最大的。当间隔基为吸电子基时，β 0 的值与吸电子能力有关，β 0 的值与间隔基的吸电子能力成反比。