基于最新势能面的C(^(1)D)+H_(2)反应的环聚合分子动力学研究

Ring Polymer Molecular Dynamics of the C(^(1)D)+H_(2) Reaction on the Most Recent Potential Energy Surfaces

本文利用环聚合分子动力学方法对C(^(1)D)+H_(2)反应开展了详细的理论研究.计算中使用了最近构建的Zhang-Ma-Bian(ZMB)从头算势能面,该势能面对锥形交叉附近区域以及范德华区域均有精确的描述.环聚合分子动力学计算得到的热反应速率常数与最新实验值吻合很好.与前人计算结果比较,发现在a^(1)A’电子基态的ZMB-a势能面上获得的反应速率常数远大于前人构建的RKHS势能面上的结果,这是由于ZMB势能面上的范德华鞍具有与之前势能面上的范德华阱完全不同的动态学作用,表明环聚合分子动力学方法能够处理范德华作用引起的势能面拓扑结构所导致的动态学效应.本文还揭示了b^(1)A"电子激发态ZMB-b势能面以及量子效应对反应的重要性.

Ring polymer molecular dynamics(RPMD)calculations for the C(^(1)D)+H_(2)reaction are performed on the Zhang-Ma-Bian ab initio potential energy surfaces(PESs)recently constructed by our group,which are unique in very good descriptions of the regions around conical intersections and of van der Waals(vdW)interactions.The calculated reaction thermal rate coefficients are in very good agreement with the latest experimental results.The rate coefficients obtained from the ground˜a^(1)A′ZMB-a PES are much larger than those from the previous RKHS PES,which can be attributed to that the vdW saddles on our PESs have very different dynamical effects from the vdW wells on the previous PESs,indicating that the RPMD approach is able to include dynamical effects of the topological structures caused by vdW interactions.The importance of the excited˜b^(1)A′′ZMB-b PES and quantum effects in the title reaction is also underscored.