三聚氰胺分子的电子吸收光谱、二阶极化率及其溶剂效应的密度泛函理论计算  

DFT calculation for electronic absorption spectra,second-order polarizability and their solvation effects of melamine

作　　者：周玲[1,2,3] 赵改云[1,2,3] 张干兵[1,2,3] 叶勇[1,2,3] 夏清华[1,2,3] 

机构地区：[1]有机化工新材料湖北省协同创新中心,湖北武汉430062 [2]有机功能分子合成与应用教育部重点实验室,湖北武汉430062 [3]湖北大学化学化工学院,湖北武汉430062

出　　处：《湖北大学学报（自然科学版）》2014年第6期564-569,共6页Journal of Hubei University：Natural Science

基　　金：有机功能分子合成与应用教育部重点实验室开放基金(2013)资助

摘　　要：结合自洽反应场(SCRF)法、CPCM溶剂化模型,分别用密度泛函理论法B3LYP、TD-DFT/CAM-B3LYP和有限场(FF)法,对三聚氰胺分子在气相、氯仿以及甲醇溶液中的几何结构、电子吸收光谱、二阶极化率进行了系统的理论计算.结果表明,该分子为准八极结构,其强吸收峰在远紫外区,透光范围宽.最大吸收由两个近简并的激发态跃迁叠加而成,二者呈加和模式,对二阶极化率都有贡献.其几何结构、电子光谱和非线性光学(NLO)极化率都不同程度地呈现溶剂效应.高极性溶剂能显著增大其超极化率,而其最大吸收红移很小.在保持分子基本架构的前提下,通过增大供体与受体核之间的共轭桥,可以在保持良好透明性的前提下,增大超极化率,得到良好的NLO生色团.Systematic calculations have been performed for the optimized geometric structure,electronic absorption spectra and hyperpolarizabilities of melamine in vacuum,chloroform and methanol solutions using density functional theory（DFT）method B3 LYP,TD-DFT/CAM-B3 LYP and finite field method（FF）combined with SCRF method via CPCM solvation model.Calculated results show that the titled molecule in various environments has pseudo-octupolar geometry;its major electronic absorption bands are located in far-ultraviolet region,offering a wide transparence area,and meeting the requirement of a good candidate for nonlinear optical（NLO）materials.It is found that the maximum absorption of the titled compound is contributed from two nearly-degenerate low-lying excited electronic states,both contributing to the second-order NLO polarizability in an additive mode. The geometry,electronic absorption spectrum,and the second-order NLO polarizability of melamine are affected by salvation to some degree.Specifically,more polar solvent can enhance the second-order nonlinear optical polarizability of the titled molecule intensively,whereas its maximum absorption wavelength shows red-shift just little. Good candidates for NLOchromophores with melamine as building block can be designed.

关 键 词：密度泛函理论计算 三聚氰胺 八极分子 电子吸收谱 二阶极化率 溶剂效应 

分 类 号：TQ572[化学工程—精细化工]