Department of Chemistry , Duke University , Durham , North Carolina 27708 , United States.
Department of Physics , University of Cyprus , 2109 Nicosia , Cyprus.
J Chem Theory Comput. 2018 Sep 11;14(9):4818-4832. doi: 10.1021/acs.jctc.8b00001. Epub 2018 Aug 22.
Infrared (IR) excitation is known to change electron-transfer kinetics in molecules. We use nonequilibrium molecular dynamics (NEqMD) simulations to explore the molecular underpinnings of how vibrational excitation may influence nonadiabatic electron-transfer. NEqMD combines classical molecular dynamics simulations with nonequilibrium semiclassical initial conditions to simulate the dynamics of vibrationally excited molecules. We combine NEqMD with electronic structure computations to probe IR effects on electron transfer rates in two molecular species, dimethylaniline-guanosine-cytidine-anthracene (DMA-GC-Anth) and 4-(pyrrolidin-1-yl)phenyl-2,6,7-triazabicyclo[2.2.2]octatriene-10-cyanoanthracen-9-yl (PP-BCN-CA). In DMA-GC-Anth, the simulations find that IR excitation of the NH scissoring motion and the subsequent intramolecular vibrational energy redistribution (IVR) do not significantly alter the mean-squared donor-acceptor (DA) coupling interaction. This finding is consistent with earlier computational analysis of static systems. In PP-BCN-CA, IR excitation of the bridging C═N bond changes the bridge-mediated coupling for charge separation and recombination by ∼30-40%. The methods described here enable detailed explorations of how IR excitation may perturb charge-transfer processes at the molecular scale.
红外（IR）激发已知会改变分子中的电子转移动力学。我们使用非平衡分子动力学（NEqMD）模拟来探索振动激发如何影响非绝热电子转移的分子基础。NEqMD 将经典分子动力学模拟与非平衡半经典初始条件相结合，以模拟振动激发分子的动力学。我们将 NEqMD 与电子结构计算相结合，以研究两种分子（二甲苯胺-鸟嘌呤-胞嘧啶-蒽（DMA-GC-Anth）和 4-（吡咯烷-1-基）苯基-2,6,7-三氮杂双环[2.2.2]辛三烯-10-氰基蒽-9-基（PP-BCN-CA））中 IR 对电子转移速率的影响。在 DMA-GC-Anth 中，模拟发现 NH 剪式运动的 IR 激发和随后的分子内振动能量重新分布（IVR）不会显著改变均方施主-受主（DA）耦合相互作用。这一发现与静态系统的早期计算分析一致。在 PP-BCN-CA 中，桥接 C=N 键的 IR 激发通过约 30-40%改变了桥接介导的电荷分离和重组的耦合。这里描述的方法能够详细探索 IR 激发如何在分子尺度上干扰电荷转移过程。
