Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University Atlanta, Georgia 30322, USA.
Chem Soc Rev. 2017 Dec 11;46(24):7615-7624. doi: 10.1039/c7cs00578d.
The phenomenon of roaming in chemical reactions has now become both commonly observed in experiment and extensively supported by theory and simulations. Roaming occurs in highly-excited molecules when the trajectories of atomic motion often bypass the minimum energy pathway and produce reaction in unexpected ways from unlikely geometries. The prototypical example is the unimolecular dissociation of formaldehyde (HCO), in which the "normal" reaction proceeds through a tight transition state to yield H + CO but for which a high fraction of dissociations take place via a "roaming" mechanism in which one H atom moves far from the HCO, almost to dissociation, and then returns to abstract the second H atom. We review below the theories and simulations that have recently been developed to address and understand this new reaction phenomenon.
化学反中 roaming 现象现在已经在实验中被普遍观察到，并得到了理论和模拟的广泛支持。当原子运动的轨迹经常绕过最低能量途径并以出人意料的方式产生反应，而且这种反应来自不太可能的几何形状时，roaming 就会发生在高激发分子中。典型的例子是甲醛（HCO）的单分子离解，其中“正常”反应通过紧密过渡态进行，生成 H + CO，但有很大一部分离解是通过“漫游”机制发生的，其中一个 H 原子从 HCO 中移动得很远，几乎要离解，然后再返回提取第二个 H 原子。下面我们将回顾最近为解决和理解这一新的反应现象而开发的理论和模拟。
