A globla potential energy surface （PES） for the H＋CH4←→H2＋CH3 reaction has been constructed using the neural networks method based on 47783 high level ab initio geometry points. Extensive quasi-classical traject...A globla potential energy surface （PES） for the H＋CH4←→H2＋CH3 reaction has been constructed using the neural networks method based on 47783 high level ab initio geometry points. Extensive quasi-classical trajectories and quantum scattering calculations were carried out to check the convergence of the PES. This PES, fully converged with respect to the fitting procedure and the number of ab initio points, has a very small fitting error, and is much faster on evaluation than the modified Shepard interpolating PES, representing the best available PES for this benchmark polyatomic system.展开更多
The time-dependent wave-packet method was employed to calculate the first full-dimensional state-to-state differential cross sections （DCS） for the title reaction with D2O in the ground and the first symmetric （100...The time-dependent wave-packet method was employed to calculate the first full-dimensional state-to-state differential cross sections （DCS） for the title reaction with D2O in the ground and the first symmetric （100） and asymmetric stretching （001） excited states. The calculated DCSs for these three initial states are strongly backward peaked at low collision energies. With the increase of collision energy, these DCSs become increasingly broader with the peak position shifting gradually to a smaller angle, consistent with the fact that the title reaction is a direct reaction via an abstraction mechanism. It is found that the （100） and （001） states not only have roughly the same integral cross sections, but also have essentially identical DCS, which are very close to that for the ground state at the same total energy of reaction. The reaction produces a small fraction of OD in the v=1 state, with the population close to the relative reactivity between the ground and vibrationally excited states, therefore confirming the experimental result of Zare et al. and the local mode picture [J. Phys. Chem. 97, 2204 （1993）]. Unexpectedly, the stretching excitation reduces the rotation excitation of product HD at the same total energy.展开更多
基金V. ACKNOWLEDGEMENTS This work was supported by the National Natural Science Foundation of China （No.90921014）, the Chinese Academy of Sciences, and the Ministry of Science and Technology of China （No.2013CB834601）.
文摘A globla potential energy surface （PES） for the H＋CH4←→H2＋CH3 reaction has been constructed using the neural networks method based on 47783 high level ab initio geometry points. Extensive quasi-classical trajectories and quantum scattering calculations were carried out to check the convergence of the PES. This PES, fully converged with respect to the fitting procedure and the number of ab initio points, has a very small fitting error, and is much faster on evaluation than the modified Shepard interpolating PES, representing the best available PES for this benchmark polyatomic system.
基金This work was supported by the National Natural Science Foundation of China （No.21403223, No.21433009, and No.91221301）, the Ministry of Science and Technology of China （No.2013CB834601）, and the Chinese Academy of Sciences.
文摘The time-dependent wave-packet method was employed to calculate the first full-dimensional state-to-state differential cross sections （DCS） for the title reaction with D2O in the ground and the first symmetric （100） and asymmetric stretching （001） excited states. The calculated DCSs for these three initial states are strongly backward peaked at low collision energies. With the increase of collision energy, these DCSs become increasingly broader with the peak position shifting gradually to a smaller angle, consistent with the fact that the title reaction is a direct reaction via an abstraction mechanism. It is found that the （100） and （001） states not only have roughly the same integral cross sections, but also have essentially identical DCS, which are very close to that for the ground state at the same total energy of reaction. The reaction produces a small fraction of OD in the v=1 state, with the population close to the relative reactivity between the ground and vibrationally excited states, therefore confirming the experimental result of Zare et al. and the local mode picture [J. Phys. Chem. 97, 2204 （1993）]. Unexpectedly, the stretching excitation reduces the rotation excitation of product HD at the same total energy.
