Identification of unavoided crossings in nonadiabatic photoexcited dynamics involving multiple electronic states in polyatomic conjugated molecules
Identification of unavoided crossings in nonadiabatic photoexcited dynamics involving multiple electronic states in polyatomic conjugated molecules
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DOI：
10.1063/1.4732536
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发表时间：
2012-07-07
影响因子：
4.4
通讯作者：
Tretiak, Sergei
中科院分区：
文献类型：
--
作者：
Fernandez-Alberti, Sebastian;Roitberg, Adrian E.;Tretiak, Sergei
多原子分子中的电子激发态之间的无辐射跃迁通过势能面的不可避免的交叉而发生，其中各个绝热态之间具有实质性的非绝热耦合。虽然这些耦合的时间范围足够大，但这些跃迁可以通过使用轨迹表面跳跃类方法的量子跃迁来合理地模拟。此外，复杂的分子系统可能有多个“平凡”的非相互作用状态之间的不可避免的交叉。在这些情况下，非绝热耦合被描述为尖锐的峰值强烈本地化的时间。因此，它们的建模通常受到识别的区域接近特定的瞬时核配置的能量表面实际上彼此交叉。在这里，我们提出了一个新的程序来识别和治疗这些区域的非相互作用的状态之间的不可避免的交叉点，使用所谓的最小成本算法。该方法区分相互作用状态之间的未避免的交叉（由量子跳跃模拟），和非相互作用状态之间的平凡的未避免的交叉（通过用最小成本过程跟踪状态来检测）。我们讨论了它的实施在我们最近开发的非绝热激发态分子动力学框架。在各种分离的两个和四个环的线性聚亚苯基乙炔基发色团单元的片段已被用作一个代表性的分子系统来测试算法。我们的研究结果使我们能够区分和分析这些不同类型的无辐射跃迁的分子系统进行内部转换的主要特点。(C)2012年美国物理学会。[http：//dx.doi.org/10.1063/1.4732536]
Radiationless transitions between electronic excited states in polyatomic molecules take place through unavoided crossings of the potential energy surfaces with substantial non-adiabatic coupling between the respective adiabatic states. While the extent in time of these couplings are large enough, these transitions can be reasonably well simulated through quantum transitions using trajectory surface hopping-like methods. In addition, complex molecular systems may have multiple "trivial" unavoided crossings between noninteracting states. In these cases, the non-adiabatic couplings are described as sharp peaks strongly localized in time. Therefore, their modeling is commonly subjected to the identification of regions close to the particular instantaneous nuclear configurations for which the energy surfaces actually cross each other. Here, we present a novel procedure to identify and treat these regions of unavoided crossings between non-interacting states using the so-called Min-Cost algorithm. The method differentiates between unavoided crossings between interacting states (simulated by quantum hops), and trivial unavoided crossings between non-interacting states (detected by tracking the states in time with Min-Cost procedure). We discuss its implementation within our recently developed non-adiabatic excited state molecular dynamics framework. Fragments of two-and four-ring linear polyphenylene ethynylene chromophore units at various separations have been used as a representative molecular system to test the algorithm. Our results enable us to distinguish and analyze the main features of these different types of radiationless transitions the molecular system undertakes during internal conversion. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4732536]