从头算分子动力学研究O-与CH_3F反应的产物通道

在B3LYP/6-31+G(d,p)理论水平下采用基于波恩-奥本海默近似的从头算分子动力学方法重新研究了O-与CH3F反应经抽氢生成OH-和生成H2O的两条产物通道.反应轨线从反应初始过渡态开始,采用300K时的热取样确定初始条件,同时为对比不同的初始碰撞平动能条件下产物通道的变化,分别限定过渡矢量上的能量为2.1、36.8及62.8kJ·mol-1进行轨线计算,所有轨线计算的结果表明抽氢生成OH-的过程始终为主要的产物通道.我们的计算不仅进一步证实了以往实验的结论,而且描绘了抽氢生成OH-和生成H2O这两个产物通道在反应出口势能面上的动态反应路径,更为深刻地揭示了该反应的微观机理.

Ab initio Molecular Dynamics Investigation on the Production Channels for the Reaction of O- with CH3F

H-atom abstraction and H₂O production channels for the reaction of O^- with CH₃F were reinvestigated using the ab initio molecular dynamics method at the B3LYP/6-31₊G(d,p) level of theory and based on the Born-Oppenheimer approximation. The reactive trajectories were initiated at the transition state of H-atom abstraction. Thermal sampling at 300 K was chosen to determine the initial conditions. Additionally, the energies added to the transition vector of the barrier were restricted to 2.1, 36.8, and 62.8 kJ·mol ^-1, separately, to reveal the impact of different initial collision energies on the reaction pathways. The results of all the trajectory calculations demonstrate that the H-atom abstraction channel is the dominant production channel. Therefore, our calculations are consistent with previous experimental conclusions. Furthermore, the dynamic reaction pathways for H-atom abstraction and the H₂O production channels on the exit-channel potential energy surface are described based on our calculations and thus a comprehensive reaction mechanismis revealed at the microscopic level.