Institute for Fundamental Chemistry, Kyoto University, 606-8103 Kyoto, Japan.
J Chem Phys. 2019 Mar 21;150(11):114101. doi: 10.1063/1.5094149.
Formation of chemical bonds is theoretically discerned by the presence of static nuclear configuration on a potential energy surface given within the Born-Oppenheimer framework. We here study dynamical chemical bonding for molecules residing in the electronic excited states that are in a densely quasi-degenerate electronic state manifold and thereby keep undergoing extremely frequent nonadiabatic transitions. For this type of the states, the notion of global potential energy surfaces based on the adiabatic representation loses the usual sense. Nonetheless, chemical bonding exists and associated chemical reactions certainly proceed, for which we call chemistry without potential surfaces. As such, we investigate the highly excited states of boron clusters, which have extraordinarily long lifetimes with neither ionization nor dissociation. The dynamical chemical bonds keep rearranging themselves without converging to a static structure, the vivid electron dynamics of which is tracked by means of the nonadiabatic electron wavepacket dynamics theory. To characterize the dynamical bonding theoretically, we propose the notion of hyper-resonance.
化学键的形成在理论上可以通过在 Born-Oppenheimer 框架内给出的势能表面上存在静态核构型来识别。我们在这里研究了处于密集准简并电子态能级中的分子的动态化学键，这些分子会经历极其频繁的非绝热跃迁。对于这种类型的状态，基于绝热表示的全局势能表面的概念失去了通常的意义。然而，化学键仍然存在，并且相关的化学反应肯定会进行，我们称之为没有势能面的化学。因此，我们研究了硼团簇的高激发态，这些团簇具有非常长的寿命，既不会电离也不会离解。动态化学键不断重新排列，而不会收敛到静态结构，通过非绝热电子波包动力学理论可以跟踪其生动的电子动力学。为了从理论上描述动态键合，我们提出了超共振的概念。
