Product energy deposition of CN plus alkane H abstraction reactions in gas and solution phases
Product energy deposition of CN plus alkane H abstraction reactions in gas and solution phases
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DOI：
10.1063/1.3595259
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发表时间：
2011-06-07
影响因子：
4.4
通讯作者：
Harvey, Jeremy N.
中科院分区：
文献类型：
--
作者：
Glowacki, David R.;Orr-Ewing, Andrew J.;Harvey, Jeremy N.
在这项工作中，我们首次报告了 CN 与多原子有机物质反应的后过渡态动力学的理论研究。利用电子结构理论、新开发的解析反应PES、最近实现的稀有事件加速算法和简正模投影方案，我们对CN + 丙烷（R1）和CN + 环己烷（R2）反应进行了准经典和经典非平衡分子动力学模拟。对于 (R2)，我们在气相和 CH2Cl2 溶剂中进行了模拟。结果分析表明，溶剂对 (R2) 反应自由能表面的扰动很小，导致溶剂中的产物能量分配类似于气相。各个气相和溶液相变分缔合过渡态的分子几何形状分布非常相似，导致新生的 HCN 在其 CH 拉伸和 HCN 弯曲坐标中都受到振动激发。这项研究强调了这样一个事实，即溶液相双分子反应后可能会出现显着的非平衡能量分布，并且尽管存在摩擦阻尼，但可能会持续数百皮秒。在描述凝聚相反应性时，常常忽略非热分布的考虑；目前有趣的观察结果在多大程度上广泛传播仍然是一个有趣的问题。 (C) 2011 年美国物理研究所。 [doi:10.1063/1.3595259]
In this work, we report the first theoretical studies of post-transition state dynamics for reaction of CN with polyatomic organic species. Using electronic structure theory, a newly developed analytic reactive PES, a recently implemented rare-event acceleration algorithm, and a normal mode projection scheme, we carried out and analyzed quasi-classical and classical non-equilibrium molecular dynamics simulations of the reactions CN + propane (R1) and CN + cyclohexane (R2). For (R2), we carried out simulations in both the gas phase and in a CH2Cl2 solvent. Analysis of the results suggests that the solvent perturbations to the (R2) reactive free energy surface are small, leading to product energy partitioning in the solvent that is similar to the gas phase. The distribution of molecular geometries at the respective gas and solution phase variational association transition states is very similar, leading to nascent HCN which is vibrationally excited in both its CH stretching and HCN bending coordinates. This study highlights the fact that significant non-equilibrium energy distributions may follow in the wake of solution phase bimolecular reactions, and may persist for hundreds of picoseconds despite frictional damping. Consideration of non-thermal distributions is often neglected in descriptions of condensed-phase reactivity; the extent to which the present intriguing observations are widespread remains an interesting question. (C) 2011 American Institute of Physics. [doi:10.1063/1.3595259]