Prlj Antonio, Begušić Tomislav, Zhang Zhan Tong, Fish George Cameron, Wehrle Marius, Zimmermann Tomáš, Choi Seonghoon, Roulet Julien, Moser Jacques-Edouard, Vaníček Jiří
Laboratory of Theoretical Physical Chemistry, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Photochemical Dynamics Group, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
J Chem Theory Comput. 2020 Apr 14;16(4):2617-2626. doi: 10.1021/acs.jctc.0c00079. Epub 2020 Mar 12.
Azulene is a prototypical molecule with an anomalous fluorescence from the second excited electronic state, thus violating Kasha's rule, and with an emission spectrum that cannot be understood within the Condon approximation. To better understand the photophysics and spectroscopy of azulene and other nonconventional molecules, we developed a systematic, general, and efficient computational approach combining the semiclassical dynamics of nuclei with electronic structure. First, to analyze the nonadiabatic effects, we complement the standard population dynamics by a rigorous measure of adiabaticity, estimated with the multiple-surface dephasing representation. Second, we propose a new semiclassical method for simulating non-Condon spectra, which combines the extended thawed Gaussian approximation with the efficient single-Hessian approach. S ← S and S ← S absorption and S → S emission spectra of azulene, recorded in a new set of experiments, agree very well with our calculations. We find that accuracy of the evaluated spectra requires the treatment of anharmonicity, Herzberg-Teller, and mode-mixing effects.
薁是一种典型分子，其从第二激发电子态发出异常荧光，因此违反了卡沙规则，并且其发射光谱无法在康登近似范围内得到解释。为了更好地理解薁和其他非常规分子的光物理和光谱学，我们开发了一种系统、通用且高效的计算方法，将原子核的半经典动力学与电子结构相结合。首先，为了分析非绝热效应，我们通过用多表面退相表示估计的绝热性的严格度量来补充标准的布居动力学。其次，我们提出了一种用于模拟非康登光谱的新半经典方法，该方法将扩展的解冻高斯近似与高效的单海森方法相结合。在一组新实验中记录的薁的S←S和S←S吸收光谱以及S→S发射光谱与我们的计算结果非常吻合。我们发现，评估光谱的准确性需要考虑非谐性、赫兹伯格 - 泰勒效应和模式混合效应。
