"Pump-probe" atom-centered density matrix propagation studies to gauge anharmonicity and energy repartitioning in atmospheric reactive adducts: case study of the OH + isoprene and OH + butadiene reaction intermediates.
"Pump-probe" atom-centered density matrix propagation studies to gauge anharmonicity and energy repartitioning in atmospheric reactive adducts: case study of the OH + isoprene and OH + butadiene reaction intermediates.
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“泵-探针”原子中心密度矩阵传播研究，用于测量大气反应加合物中的非和谐性和能量重新分配：OH 异戊二烯和 OH 丁二烯反应中间体的案例研究。
DOI：
10.1021/jp212330e
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S. Iyengar
中科院分区：
文献类型：
--
作者：
Alexander B. Pacheco;Scott M. Dietrick;P. Stevens;S. Iyengar
采用时间分辨的“泵-探针”从头算分子动力学方法研究了挥发性有机化合物与羟基自由基相互作用过程中反应中间体的稳定性、能量转移和能量再分配机制。这些系统在大气层中至关重要。具体而言，异戊二烯和丁二烯分子的羟基自由基加合物的反应中间体的稳定性被用作一个案例研究，开发新的计算技术，涉及“泵探测”从头算分子动力学。从异戊二烯和丁二烯的各种可能的羟基自由基加合物开始，用过量能量填充每个加合物的选择振动模式以模拟实验的初始条件。能量流到其余的模式，然后探测受激发的加合物从头算分子动力学模拟。结果发现，加合物的稳定性直接产生由于anemically驱动耦合的模式，以促进多余的振动能量的再分配。这种振动再分配对能量密度有着至关重要的影响。
Time-resolved "pump-probe" ab initio molecular dynamics studies are constructed to probe the stability of reaction intermediates, the mechanism of energy transfer, and energy repartitioning, for moieties involved during the interaction of volatile organic compunds with hydroxyl radical. These systems are of prime importance in the atmosphere. Specifically, the stability of reaction intermediates of hydroxyl radical adducts to isoprene and butadiene molecules is used as a case study to develop novel computational techniques involving "pump-probe" ab initio molecular dynamics. Starting with the various possible hydroxyl radical adducts to isoprene and butadiene, select vibrational modes of each of the adducts are populated with excess energy to mimic the initial conditions of an experiment. The flow of energy into the remaining modes is then probed by subjecting the excited adducts to ab initio molecular dynamics simulations. It is found that the stability of the adducts arises directly due to the anhormonically driven coupling of the modes to facilitate repartitioning of the excess vibrational energy. This kind of vibrational repartitioning has a critical influence on the energy density.