旋转异构和键长变化对溶液中FTC分子光谱性质的影响

采用含时密度泛函理论结合极化连续模型计算了不同溶剂环境下FTC分子各旋转异构体的单光子吸收光谱. 结果显示在气态和溶剂中，各异构体的最大吸收波长均存在大约30 nm的差别. 在不同溶剂中，各异构体的能量次序和相应的玻尔兹曼统计分布几率发生了较大变化. 基于Hartee-Fock方法优化的结构，计算了玻尔兹曼统计平均吸收光谱，结果与实验符合得很好. 计算表明，对于所研究的分子体系，键长变化对分子的光谱性质有重要影响.

Effects of Rotational Isomerism and Bond Length Alternation on Optical Spectra of FTC Chromophore in Solution

Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-dimethyl-2,5-dihydrofuran （FTC） in a few solvents have been studied using the time-dependent density functional theory in combination with the polarizable continuum model. It is shown that the maximum absorption peaks of the ro-tamers have difference of nearly 30 nm both in vacuum and in solutions. The population of the rotamers changes a lot in different solvents. Based on the geometries optimized by Hartree-Fock method, the Maxwell-Boltzmann averaged absorption has been calculated and the maximum absorption peak is in good agreement with experiment. It indicates that the bond length alternation can have an important effect on the optical spectra.