A quasiclassical trajectory study of reactivity and product energy disposal in H+H2O, H+D2O, and H+HOD
A quasiclassical trajectory study of reactivity and product energy disposal in H+H2O, H+D2O, and H+HOD
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DOI：
10.1063/1.1366334
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发表时间：
2001-05-15
影响因子：
4.4
通讯作者：
Schatz, GC
中科院分区：
文献类型：
--
作者：
Troya, D;González, M;Schatz, GC
利用准经典轨迹（QCT）计算和新近发展的势能面，研究了H + H2O—>H-2 + OH和一些同位素对应反应的动力学[j]。物理学报，113,3150(2000)]，这是由高质量的从头计算得出的。我们与QCT和基于其他表面的量子散射结果，特别是Ochoa和Clary的结果以及实验结果进行了广泛的比较。我们的结果表明，与先前的理论结果一致，平移热氢原子与基态H2O（生成H-2 + OH）和基态D2O（生成HD + OD）反应的截面明显小于实验结果。我们的结果与相对精确表面上的精确量子结果一致，从而表明与实验的不一致既不是动力学方法的问题，也不是势表面的问题。与此相反，反应动力学的其他性质与实验结果基本一致。例如，拉伸激发对H + D2O截面的作用符合实验中观察到的趋势。发现弯曲激发在增强反应性方面比以前认为的更活跃，但仍在实验不确定范围内。在样品j（H2O）值大于等于5的实验中，发现水的旋转起重要作用。我们对H + D2O和H + HOD—b> H-2 + OD，HD + OH反应的研究得出的同位素分支比和产物分布（对于旁观者和新形成的硅藻）与实验基本一致。唯一的例外是H + D2O中的HD旋转分布，观测到的分布表现出较少的激发和较宽的分布。还讨论了实验未解析产物的内部分布。我们得出结论，这里使用的新势能面非常准确地描述了H + H2O ->H-2 + OH反应和同位素对应反应，比以前发表的结果有了显著的改进。(C) 2001年美国物理研究所。
The dynamics of the H + H2O -->H-2 + OH, and some isotopic counterpart reactions has been investigated by quasiclassical trajectory (QCT) calculations, and using a recently developed potential energy surface [Wu , J. Chem. Phys. 113, 3150 (2000)] that was derived from high quality ab initio calculations. We make an extensive comparison with QCT and quantum scattering results based on other surfaces, particularly that from Ochoa and Clary, as well as with experimental results. Our results show that, in agreement with earlier theoretical results, the cross sections for the reaction of translationally hot hydrogen atoms with ground state H2O (yielding H-2 + OH) and with ground state D2O (yielding HD + OD) are significantly smaller than experiment. Our results are in agreement with accurate quantum results on comparably accurate surfaces, thereby showing that the disagreement with experiment is not a problem with either the dynamics method or the potential surfaces. In contrast to this, other properties of the reaction dynamics are in generally excellent agreement with experiment. For example, the role of stretch excitation on the H + D2O cross sections follows the trends observed in the experiments. Bend excitation is found to be more active than was previously thought in enhancing reactivity, but is still within experimental uncertainty. Water rotation is found to play an important role in experiments that sample j(H2O) values of 5 or greater. Our studies of the H + D2O and H + HOD -->H-2 + OD,HD + OH reactions yield isotope branching ratios and product distributions (for both spectator and newly formed diatoms) that are generally in good agreement with experiment. The only exception to this arises with the HD rotational distributions in H + D2O, where the observed distributions show less excitation and broader distributions. The internal distributions of experimentally unresolved products are also discussed. We conclude that the new potential energy surface used here is very accurate for describing the H + H2O -->H-2 + OH reaction and isotopic counterparts, providing significant improvement over previously published results. (C) 2001 American Institute of Physics.