Zhang Shuwen, Chen Qixin, Zhang Lidong, Li Jun, Hu Xixi, Xie Daiqian
Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China; State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China.
Phys Chem Chem Phys. 2024 Feb 28;26(9):7351-7362. doi: 10.1039/d3cp05811e.
The CH + OH reaction is an important acetylene oxidation pathway in the combustion process, as well as a typical multi-well and multi-channel reaction. Here, we report an accurate full-dimensional machine learning-based potential energy surface (PES) for the CH + OH reaction at the UCCSD(T)-F12b/cc-pVTZ-F12 level, based on about 475 000 points. Extensive quasi-classical trajectory (QCT) calculations were performed on the newly developed PES to obtain detailed dynamic data and analyze reaction mechanisms. Below 1000 K, the CH + OH reaction produces H + OCCH and CO + CH. With increasing temperature, the product channels HO + CH and H + HCCOH are accessible and the former dominates above 1900 K. It is found that the formation of HO + CH is dominated by a direct reaction process, while other channels belong to the indirect mechanism involving long-lived intermediates along the reaction pathways. At low temperatures, the CH + OH reaction behaves like an unimolecular reaction due to the unique PES topographic features, of which the dynamic features are similar to the decomposition of energy-rich complexes formed by CH + OH collision. The classification of trajectories that undergo different reaction pathways to generate each product and their product energy distributions were also reported in this work. This dynamic information may provide a deep understanding of the CH + OH reaction.
CH + OH反应是燃烧过程中一条重要的乙炔氧化途径，也是一个典型的多阱多通道反应。在此，我们基于约475000个点，在UCCSD(T)-F12b/cc-pVTZ-F12水平上报告了CH + OH反应精确的全维机器学习势能面（PES）。在新开发的PES上进行了广泛的准经典轨迹（QCT）计算，以获得详细的动力学数据并分析反应机理。低于1000 K时，CH + OH反应生成H + OCCH和CO + CH。随着温度升高，产物通道HO + CH和H + HCCOH变得可行，且前者在1900 K以上占主导。研究发现，HO + CH的形成由直接反应过程主导，而其他通道属于沿着反应路径涉及长寿命中间体的间接机理。在低温下，由于独特的PES地形特征，CH + OH反应表现得像单分子反应，其动力学特征类似于CH + OH碰撞形成的富能复合物的分解。这项工作还报告了经历不同反应路径生成每种产物的轨迹分类及其产物能量分布。这些动力学信息可能有助于深入理解CH + OH反应。
