Department Chemie, Ludwig-Maximilians-Univerisität, München Butenandtstr. 11, 81377 München, Germany.
J Chem Phys. 2012 Aug 21;137(7):074101. doi: 10.1063/1.4745183.
The knowledge of conical intersection seams is important to predict and explain the outcome of ultrafast reactions in photochemistry and photobiology. They define the energetic low-lying reachable regions that allow for the ultrafast non-radiative transitions. In complex molecules it is not straightforward to locate them. We present a systematic approach to predict conical intersection seams in multifunctionalized polyenes and their sensitivity to substituent effects. Included are seams that facilitate the photoreaction of interest as well as seams that open competing loss channels. The method is based on the extended two-electron two-orbital method [A. Nenov and R. de Vivie-Riedle, J. Chem. Phys. 135, 034304 (2011)]. It allows to extract the low-lying regions for non-radiative transitions, which are then divided into small linear segments. Rules of thumb are introduced to find the support points for these segments, which are then used in a linear interpolation scheme for a first estimation of the intersection seams. Quantum chemical optimization of the linear interpolated structures yields the final energetic position. We demonstrate our method for the example of the electrocyclic isomerization of trifluoromethyl-pyrrolylfulgide.
锥面交叉 seam 的知识对于预测和解释光化学和光生物学中超快反应的结果非常重要。它们定义了允许超快非辐射跃迁的低能可达区域。在复杂分子中，找到它们并不容易。我们提出了一种系统的方法来预测多功能聚烯中的锥面交叉 seam 及其对取代基效应的敏感性。其中包括有利于感兴趣光反应的 seam 以及打开竞争损耗通道的 seam。该方法基于扩展的双电子双轨道方法 [A. Nenov 和 R. de Vivie-Riedle, J. Chem. Phys. 135, 034304 (2011)]。它允许提取非辐射跃迁的低能区域，然后将这些区域分成小的线性段。引入了一些经验法则来找到这些线段的支撑点，然后在线性插值方案中使用这些支撑点来对交叉 seam 进行初步估计。线性插值结构的量子化学优化给出了最终的能量位置。我们以三氟甲基吡咯fulgide 的电环化异构化为例演示了我们的方法。
