New Stress Test for Ring Polymer Molecular Dynamics: Rate Coefficients of the O(3P) + HCl Reaction and Comparison with Quantum Mechanical and Quasiclassical Trajectory Results
New Stress Test for Ring Polymer Molecular Dynamics: Rate Coefficients of the O(3P) + HCl Reaction and Comparison with Quantum Mechanical and Quasiclassical Trajectory Results
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DOI：
10.1021/acs.jpca.9b06695
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发表时间：
2019-09-19
影响因子：
2.9
通讯作者：
Aoiz, F. J.
中科院分区：
文献类型：
--
作者：
Menendez, M.;Jambrina, P. G.;Aoiz, F. J.
在过去的十年中，环状聚合物分子动力学（RPMD）已成为一个非常有效的方法来确定各种化学反应的热速率系数。本工作提出了应用这种方法来研究O（P-3）+ HCl反应，这构成了一个严格的测试，任何动力学计算，由于丰富的共振结构和其他动力学特征。将Ramachandran和Peterson [J. Chem.Phys.2003，119，9590]在（3）A“和（3）A "势能面（PES）上使用RPMD和准经典轨迹（QCT）计算的速率系数与Xie等人[J. Chem.Phys.2005，122]的现有实验和量子力学（QM）结果进行比较。014301]。该协议是非常好的T > 600 K，虽然RPMD低估率系数的一个因素之间的4和2在200-500 K的间隔。这些差异的起源在于隧道效应对（3）A "PES的贡献很大，这是由于在货车范德华威尔斯阱中的准束缚态的共振而增强的。尽管RPMD甚至在交叉温度以下也能很好地解释隧道效应，但该方法中不包括共振效应（一种长期效应）。在这项工作中研究的最高温度下，2000-3300 K，RPMD速率系数略大于QM的，但这是由于在QM计算的限制和RPMD被认为是更可靠的。
In the past decade, ring polymer molecular dynamics (RPMD) has emerged as a very efficient method to determine thermal rate coefficients for a great variety of chemical reactions. This work presents the application of this methodology to study the O(P-3) + HCl reaction, which constitutes a stringent test for any dynamical calculation due to rich resonant structure and other dynamical features. The rate coefficients, calculated on the (3)A' and (3)A '' potential energy surfaces (PESs) by Ramachandran and Peterson [J. Chem. Phys. 2003, 119, 9590], using RPMD and quasiclassical trajectories (QCT) are compared with the existing experimental and the quantum mechanical (QM) results by Xie et al. [J. Chem. Phys. 2005 122, 014301]. The agreement is very good at T > 600 K, although RPMD underestimates rate coefficients by a factor between 4 and 2 in the 200-500 K interval. The origin of these discrepancies lies in the large contribution from tunneling on the (3)A '' PES, which is enhanced by resonances due to quasibound states in the van der Waals wells. Although tunneling is fairly well accounted for by RPMD even below the crossover temperature, the effect of resonances, a long-time effect, is not included in the methodology. At the highest temperatures studied in this work, 2000-3300 K, the RPMD rate coefficients are somewhat larger than the QM ones, but this is shown to be due to limitations in the QM calculations and the RPMD are believed to be more reliable.