A general method for computing kinetic isotope effects is described. The method uses the quantum-instanton approximation and is based on the thermodynamic integration with respect to the mass of the isotopes and on the path-integral Monte-Carlo evaluation of relevant thermodynamic quantities. The central ingredients of the method are the Monte-Carlo estimators for the logarithmic derivatives of the partition function and the delta-delta correlation function. Several alternative estimators for these quantities are described here and their merits are compared on the benchmark hydrogen-exchange reaction, H+H_2->H_2+H on the Truhlar-Kuppermann potential energy surface. Finally, a qualitative discussion of issues arising in many-dimensional systems is provided.
Tunneling phase diagram: A machine-learning framework for multidimensional kinetic isotope effects
Institute of Atomic and Molecular Physics, Jilin University（吉林大学原子与分子物理研究所）；Key Laboratory of Material Simulation Methods & Software of Ministry of Education, College of Physics, Jilin University（吉林大学物理学院教育部材料模拟方法与软件重点实验室）
Three applications of path integrals: equilibrium and kinetic isotope effects, and the temperature dependence of the rate constant of the [1,5] sigmatropic hydrogen shift in (Z)-1,3-pentadiene
Laboratory Studies on the Carbon Kinetic Isotope Effects on the Production Mechanism of Particulate Phenolic Compounds Formed by Toluene Photooxidation: A Tool to Constrain Reaction Pathways
Energy-dependent normal and unusually large inverse chlorine kinetic isotope effects of simple chlorohydrocarbons in collision-induced dissociation by gas chromatography-tandem mass spectrometry
Quantum Transition State Theory for proton transfer reactions in enzymes
我们考虑了量子效应在酶催化反应中类氢物种转移中的作用。这项研究是刺激的索赔，所观察到的幅度和温度依赖性的动力学同位素效应意味着量子隧穿低于与过渡态相关的能垒显着提高反应速率在许多酶。我们使用一个路径积分的方法，它提供了一个通用的框架来理解隧道在量子系统中，在非零温度与环境相互作用。在这里，量子系统是酶的活性位点，环境是周围的蛋白质和水。低于势垒的温度仅在温度低于温度$T_0$时才发生击穿，温度势能面的曲率决定了势垒顶部附近的温度。我们认为，对于大多数酶来说，这个温度低于室温。对于物理上合理的参数，量子过渡态理论给出了两类酶的动力学同位素效应的温度依赖性和大小的定量描述，这两类酶被认为表现出量子隧穿的特征。唯一的量子效应是与过渡态相关的，包括势垒顶部的反射和势垒下方的隧穿。我们确定，由于环境的摩擦是微弱的，只有轻微的修改反应速率。此外，在室温下，对于典型的能量势垒，频率远小于1000 cm $^{-1}$的环境自由度对反应速率的量子校正没有显著影响。
Theory of proton coupled electron transfer reactions: Assessing the Born-Oppenheimer approximation for the proton motion using an analytically solvable model
