How do London Dispersion Interactions Impact the Photochemical Processes of Molecular Switches?
How do London Dispersion Interactions Impact the Photochemical Processes of Molecular Switches?
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DOI：
10.1021/acs.jpclett.7b03316
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发表时间：
2018-02-01
影响因子：
5.7
通讯作者：
Corminboeuf, Clemence
中科院分区：
文献类型：
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作者：
Fabrizio, Alberto;Corminboeuf, Clemence
在过去的二十年里，线性响应含时密度泛函理论（LR-TDDFT）已成为计算原子和分子激发态性质的最广泛使用的方法之一。尽管它成功地描述了绝大多数分子系统的光化学和光物理学，但它的适用范围受到几个实质性缺点的限制。LR-TDDFT的常见问题包括对里德堡态、电荷转移激发态、双激发态和近简并态的正确描述。除了这些公认的缺点，LR-TDDFT中使用的近似泛函无法完全描述伦敦色散相互作用。在这项工作中，我们的目标是了解货车德瓦耳斯相互作用的化学系统的性质超越其电子基态的影响。为此，我们比较了原型顺式二苯乙烯分子及其3- 3 '，5 - 5'-四叔丁基衍生物的激发态能量分布和动力学轨迹的结果。虽然明确的治疗伦敦分散相互作用的结果可以忽略不计的变化，为顺式芪，我们表明，这些吸引力的取代衍生物的能量和结构演变有重大影响。在后一种情况下，分子内分散相互作用影响的模拟结果定性，导致增加的优先选择的光环化途径。这项工作的方法的后果并不唯一适用于说明性的芪的情况下。事实上，这种分子代表了一整类化学情况，其中色散力主导了光激发发色团的未激发取代基之间的相互作用。例如，这是有机光致发光中的常见情况，其中供体分子通常用长烷基侧链官能化以改善溶解性和组装。
In the last two decades, linear-response time-dependent density functional theory (LR-TDDFT) has become one of the most widely used approaches for the computation of the excited-state properties of atoms and molecules. Despite its success in describing the photochemistry and the photophysics of a vast majority of molecular systems, its domain of applicability has been limited by several substantial drawbacks. Commonly identified problems of LR-TDDFT include the correct description of Rydberg states, charge-transfer excited states, doubly excited states, and nearly degenerate states. In addition to these widely recognized shortcomings, the approximate functionals used in LR-TDDFT are unable to fully describe London dispersion interactions. In this work, we aim at understanding the impact of van der Waals interactions on the properties of chemical systems beyond their electronic ground state. For this purpose, we compare the results of excited-state energy profiles and dynamic trajectories for the prototypical cis-stilbene molecule with its 3-3',5-5'-tetra-tert-butyl derivative. While the explicit treatment of London dispersion interactions results in negligible changes for the cis-stilbene, we show that these attractive forces have a substantial influence on the energetics and structural evolution of the substituted derivative. In the latter case, intramolecular dispersion interactions impact the outcome of the simulation qualitatively, leading to an increased preference for the photocyclization pathway. The methodological consequences of this work are not uniquely applicable to the illustrative stilbene case. In fact, this molecule is representative of a whole class of chemical situations, where dispersion forces dominate the interactions between the unexcited substituents of a photoexcited chromophore. This is, for instance, a common situation in organic photovoltaics where donor molecules are usually functionalized with long alkyl side chains to improve solubility and assembly.