Liu Shu, Chen Jun, Zhang Xiaoren, Zhang Dong H
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian Liaoning 116023 China
University of Chinese Academy of Sciences Beijing 100049 China.
Chem Sci. 2023 Jun 24;14(29):7973-7979. doi: 10.1039/d3sc02629a. eCollection 2023 Jul 26.
The signature of dynamics resonances was observed in the benchmark polyatomic F + CH/CHD reactions more than a decade ago; however, the dynamical origin of the resonances is still not clear due to the lack of reliable quantum dynamics studies on accurate potential energy surfaces. Here, we report a six-dimensional state-to-state quantum dynamics study on the F + CHD → HF + CD reaction on a highly accurate potential energy surface. Pronounced oscillatory structures are observed in the total and product rovibrational-state-resolved reaction probabilities. Detailed analysis reveals that these oscillating features originate from the Feshbach resonance states trapped in the peculiar well on the HF(' = 3)-CD vibrationally adiabatic potential caused by HF chemical bond softening. Most of the resonance structures on the reaction probabilities are washed out in the well converged integral cross sections (ICS), leaving only one distinct peak at low collision energy. The calculated HF vibrational state-resolved ICS for CD( = 0) agrees quantitatively with the experimental results, especially the branching ratio, but the theoretical CD umbrella vibration state distribution is found to be much hotter than the experiment.
十多年前，在基准多原子F + CH/CHD反应中观察到了动力学共振的特征；然而，由于缺乏在精确势能面上进行可靠的量子动力学研究，共振的动力学起源仍不清楚。在此，我们报告了在高精度势能面上对F + CHD → HF + CD反应进行的六维态-态量子动力学研究。在总的和产物振转态分辨的反应概率中观察到明显的振荡结构。详细分析表明，这些振荡特征源于被困在由HF化学键软化引起的HF（' = 3）-CD振动绝热势中特殊阱内的费什巴赫共振态。反应概率上的大多数共振结构在阱收敛的积分截面（ICS）中被消除，在低碰撞能量下仅留下一个明显的峰。计算得到的CD（ = 0）的HF振动态分辨的ICS与实验结果在定量上相符，特别是分支比，但发现理论上的CD伞形振动态分布比实验结果热得多。
