Yang Pei-Yun, Cao Jianshu
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
J Phys Chem Lett. 2021 Oct 7;12(39):9531-9538. doi: 10.1021/acs.jpclett.1c02210. Epub 2021 Sep 27.
The electromagnetic field in an optical cavity can dramatically modify and even control chemical reactivity via vibrational strong coupling (VSC). Since the typical vibration and cavity frequencies are considerably larger than thermal energy, it is essential to adopt a quantum description of cavity-catalyzed adiabatic chemical reactions. Using quantum transition state theory (TST), we examine the coherent nature of adiabatic reactions in cavities and derive the cavity-induced changes in eigenfrequencies, zero-point energy, and quantum tunneling. The resulting quantum TST calculation allows us to explain and predict the resonance effect (i.e., maximal kinetic modification via tuning the cavity frequency), collective effect (i.e., linear scaling with the molecular density), and selectivity (i.e., cavity-induced control of the branching ratio). The TST calculation is further supported by perturbative analysis of polariton normal modes, which not only provides physical insights to cavity-catalyzed chemical reactions but also presents a general approach to treat other VSC phenomena.
光学腔中的电磁场可通过振动强耦合（VSC）显著改变甚至控制化学反应活性。由于典型的振动频率和腔频率远大于热能，因此采用量子描述腔催化的绝热化学反应至关重要。利用量子过渡态理论（TST），我们研究了腔中绝热反应的相干性质，并推导了腔诱导的本征频率、零点能量和量子隧穿的变化。由此产生的量子TST计算使我们能够解释和预测共振效应（即通过调节腔频率实现最大动力学修饰）、集体效应（即与分子密度呈线性比例关系）和选择性（即腔诱导的分支比控制）。TST计算进一步得到了极化激元正常模式微扰分析的支持，这不仅为腔催化化学反应提供了物理见解，还提出了一种处理其他VSC现象的通用方法。
