Theory of thermally activated polaritonic chemistry

极化子化学是化学、材料科学和光子学交叉的一个新兴学科。它的主要目标是通过将分子或分子系综耦合到受限的电磁场来引导和控制反应过程的性质，如产率、选择性和速率。这种受限的电磁场可以通过各种方式实现，例如通过由光反射表面封闭的空腔。 最近的实验在微腔[托马斯等。艾尔，安琪。Chem.55，11462（2016）]报道了由于与反应物和过渡态的分子振动耦合的受限电磁模式的影响，热速率常数的重要修改。 目前，振动耦合腔系综混合系统影响热化学反应的机制知之甚少。例如，涉及耦合到腔的分子的实验速率测量已经通过传统过渡态理论的玻璃解释，从而提取，例如，热力学和熵对总热速率常数的贡献。然而，这些实验的解释是滑的，作为一个微观的图片，解释在这样的系统中的相互作用和能量再分配机制，和一个微观的反应速率理论，可以解释这些rates，missing.因此，本项目的主要目的是推进对振动耦合腔分子系综（VCE）中的热激活化学反应的理论理解。这包括三个主要领域：（I）腔分子系综红外光谱的表征和计算相应光谱的理论方法的开发;（2）发展能量再分配过程和由腔模介导的耦合的微观图像，这些过程和耦合对改变其反应特性有影响;计算化学反应速率，包括腔耦合的影响。在这些领域的进展将使未来的进展，无论是实验和理论，在方向上的转向和控制化学反应中存在的限制电磁场。

Polaritonic chemistry is an emerging paradigm at the intersections of chemistry, materials science and photonics. Its main promise is to steer and control the properties of reactive processes such as yield, selectivity and rates through the coupling of molecules or molecular ensembles to confined electromagnetic fields.Such confined electromagnetic fields can be realised in various ways, for example by cavities enclosed by light-reflecting surfaces. Recent experiments in micro-cavities [Thomas et. al, Angew. Chem. 55, 11462 (2016)] report important modifications of thermal rate constants owing to the effect of confined electromagnetic modes coupled to molecular vibrations of the reactants and transition state. Currently, the mechanisms by which vibrationally coupled cavity-ensemble hybrid systems affect thermal chemical reactions are poorly understood. For example, experimental rate measurements involving molecules coupled to a cavity have been interpreted through the glass of traditional transition state theory, thus extracting, e.g., enthalpic and entropic contributions to the total thermal rate constant. However, these experimental interpretations are slippery, as a microscopic picture that explains the interactions and energy redistribution mechanisms in such systems, and a microscopic reaction rate theory that can explain those rates, are missing.The main aim of this project is hence to advance towards a theoretical understanding of thermally activated chemical reactions in vibrationally coupled cavity-molecular ensembles (VCE). This encompasses three main areas: (I) characterisation of the infrared spectroscopy of cavity-molecular ensembles and development of theoretical approaches to calculate the corresponding spectra; (2) development of a microscopic picture of the energy redistribution processes and couplings mediated by the cavity mode(s) and which have an effect in modifying its reactive properties and (3) calculation of chemical reaction rates that include the effects of the cavity coupling.Advances in these areas shall enable future progress, both experimental and theoretical, in the directions of steering and controlling chemical reactions in the presence of confined electromagnetic fields.