Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, Karnataka, India.
J Phys Chem B. 2022 Aug 4;126(30):5629-5636. doi: 10.1021/acs.jpcb.2c03273. Epub 2022 Jul 27.
The slow power law decay of the velocity autocorrelation function of a particle moving stochastically in a condensed-phase fluid is widely attributed to the momentum that fluid molecules displaced by the particle transfer back to it during the course of its motion. The forces created by this backflow effect are known as Basset forces, and they have been found in recent analytical work and numerical simulations to be implicated in a number of interesting dynamical phenomena, including boosted particle mobility in tilted washboard potentials. Motivated by these findings, the present paper is an investigation of the role of backflow in thermally activated barrier crossing, the governing process in essentially all condensed-phase chemical reactions. More specifically, it is an exact analytical calculation, carried out within the framework of the reactive-flux formalism, of the transmission coefficient κ() of a Brownian particle that crosses an inverted parabola under the influence of a colored noise process originating in the Basset force and a Markovian time-local friction. The calculation establishes that κ() is significantly enhanced over its backflow-free limit.
在凝聚相流体中随机运动的粒子的速度自相关函数的缓慢幂律衰减，通常归因于在粒子运动过程中被粒子移开的流体分子传递回它的动量。这种回流效应产生的力被称为巴塞特力，最近的分析工作和数值模拟发现，它们与许多有趣的动力学现象有关，包括倾斜搓板势中粒子迁移率的提高。受这些发现的启发，本文研究了回流在热激活势垒穿越中的作用，这是本质上所有凝聚相化学反应的控制过程。更具体地说，这是在反应通量形式主义的框架内进行的布朗粒子的传输系数 κ()的精确解析计算，该布朗粒子在由巴塞特力和马尔可夫时间局部摩擦引起的有色噪声过程的影响下穿过倒抛物线。该计算确定 κ()明显高于其无回流限制的情况。
