Full-dimensional and reduced-dimensional calculations of initial state-selected reaction probabilities studying the H + CH4 → H2 + CH3 reaction on a neural network PES.
Full-dimensional and reduced-dimensional calculations of initial state-selected reaction probabilities studying the H + CH4 → H2 + CH3 reaction on a neural network PES.
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DOI：
10.1063/1.4906825
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发表时间：
2015-02
期刊：
影响因子：
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通讯作者：
R. Welsch;U. Manthe
中科院分区：
文献类型：
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作者：
R. Welsch;U. Manthe
在最近的神经网络势的基础上，计算了H+CH4-→H2+CH3反应的初态选择反应几率[X.Xu，J.Chen，and D.H.Zhang，Chin.J·化学。太棒了。27,373(2014)]。量子动力学计算采用量子过渡态概念和多层多组态含时Hartree方法，严格研究了总角动量(J=0)为零的反应。这些计算考察了神经网络电势的准确性，并研究了降维处理所产生的影响。神经网络势的计算结果与Shepard插值势能面的计算结果吻合较好。降维计算只考虑了8个自由度的运动，并保留了甲基碎片的C3v对称性。考虑从甲烷的振动基态出发的反应，降维计算的反应几率比全维计算的反应几率在能量上略有移动，但在其他方面符合得很好。如果考虑甲烷反应物在类似类型的振动激发下的平均反应概率，也会发现类似的一致。相反，对于从甲烷的对称伸展、不对称(f2对称)伸缩或e对称弯曲激发态开始的反应几率，简化和全维结果之间存在显著差异。
Initial state-selected reaction probabilities of the H + CH4 → H2 + CH3 reaction are calculated in full and reduced dimensionality on a recent neural network potential [X. Xu, J. Chen, and D. H. Zhang, Chin. J. Chem. Phys. 27, 373 (2014)]. The quantum dynamics calculation employs the quantum transition state concept and the multi-layer multi-configurational time-dependent Hartree approach and rigorously studies the reaction for vanishing total angular momentum (J = 0). The calculations investigate the accuracy of the neutral network potential and study the effect resulting from a reduced-dimensional treatment. Very good agreement is found between the present results obtained on the neural network potential and previous results obtained on a Shepard interpolated potential energy surface. The reduced-dimensional calculations only consider motion in eight degrees of freedom and retain the C3v symmetry of the methyl fragment. Considering reaction starting from the vibrational ground state of methane, the reaction probabilities calculated in reduced dimensionality are moderately shifted in energy compared to the full-dimensional ones but otherwise agree rather well. Similar agreement is also found if reaction probabilities averaged over similar types of vibrational excitation of the methane reactant are considered. In contrast, significant differences between reduced and full-dimensional results are found for reaction probabilities starting specifically from symmetric stretching, asymmetric (f2-symmetric) stretching, or e-symmetric bending excited states of methane.