The rate of a chemical reaction can often be determined by the properties of a rank-1 saddle and the associated transition state separating reactants and products. We have found evidence that such rates can be controlled and even enhanced by external driving in at least one such system. Specifically, we analyze a reactive model in two degrees of freedom that has been used earlier to describe driven chemical reactions. Therein, changes in the external driving can lead to a local maximum of the decay rate constant or even to bifurcations of periodic trajectories on the normally hyperbolic invariant manifold (NHIM) corresponding to the transition state. Inspired by these bifurcations, we show that in this case, the dynamics on the NHIM can be connected to the geometry of reactive trajectories and to reaction probabilities of Maxwell–Boltzmann distributed reactant ensembles.

化学反应的速率通常可以由 1 级鞍的性质和相关的过渡态分离反应物和产物来确定。我们已经发现证据表明，在至少一个这样的系统中，可以通过外部驱动来控制甚至提高这种速率。具体来说，我们分析了一个早先用于描述驱动化学反应的两个自由度的反应模型。其中，外部驱动的变化会导致衰减率常数的局部最大值，甚至导致对应于过渡态的常双曲不变流形 (NHIM) 上周期性轨迹的分叉。受这些分叉的启发，我们表明，在这种情况下，