We report dynamics studies of cyclopentadiene dimerization. Transition structures were re-optimized with different density functionals. All but M06-2X give the ambimodal transition state. With ZPE, M06-2X also gives an ambimodal structure. Dynamics results show that 70% of the trajectories are dynamically-concerted, possessing a time gap between formation of two bonds smaller than 60 fs, which is the lifetime of transition state at room temperature from Eyring’s transition state theory. Thirty percent are dynamically stepwise. A “Two-stage” mechanism was found in 13% of the total trajectories. These are part of the dynamically stepwise trajectories and follow pathways through the Cope transition state hypothesized by Woodward and Katz in 1959. These are categorized as dynamically-stepwise trajectories since there are multiple vibrations before the second bond formation is completed. Dynamically-stepwise trajectories increase to 72% when the temperature of the simulation is set to 1000 K. More deep-recrossing trajectories are detected when trajectories were studied at this temperature.

我们报告了环戊二烯二聚化的动力学研究。使用不同的密度功能对过渡结构进行了重新优化。除M06-2X以外的所有元件都给出了双峰过渡状态。使用ZPE，M06-2X还具有双峰结构。动力学结果表明，70％的轨迹是动态一致的，形成两个键之间的时间间隔小于60 fs，这是根据Eyring过渡态理论得出的室温下过渡态的寿命。30％是动态逐步的。在总轨迹的13％中发现了“两阶段”机制。这些是动态逐步轨迹的一部分，并遵循通过以下假设的Cope过渡态的路径：伍德沃德（Woodward）和卡茨（Katz）于1959年提出。由于第二次键合形成之前存在多次振动，因此将它们归类为动态逐步轨迹。当将模拟温度设置为1000 K时，动态步进轨迹会增加到72％。在此温度下研究轨迹时，会检测到更多的深度交叉轨迹。