Joint Theoretical Study on Quantum Rate Processes

我们采用了通量-通量互相关函数方法（CCFA）来计算自相关函数方法（ACFA）不适用的反应的量子热速率常数。在前一种方法中，两个划分表面将系统划分为三个区域，而在后一种方法中，两个通道由一个划分表面限定。因此，CCFA方法适用于多通道反应。在本文中，我们展示了CCFA的效率，多通道反应，并将其扩展到表面反应，那里有无限数量的本地化通道。例如，我们采用了在两个势垒之间的阱中形成稳定络合物的模型，并研究了氢原子在Cu（111）表面上的自扩散。在前一个反应中，除了定义复杂的通道，互相关函数可以避免在ACFA中看到的振荡。在后一个反应中，我们引入封闭的划分表面，细分每个通道的势能面。封闭的分割表面和CCFA的组合提供了明确定义的速率常数为单和多跳速率。

We have employed a flux-flux cross-correlation function approach (CCFA) to calculate the quantum thermal rate constants of reactions for which an auto-correlation function, approach (ACFA) is not adequate. In the former approach, two dividing surfaces partition a system into three regions, while in the latter approach, two channels are defined by a dividing surface. Therefore, the CCFA method is appropriate for multi-channel reactions. In this paper, we show the efficiency of the CCFA to multi-channel reactions, and extend it to surface reactions, where there are an infinite number of localized channels. For example, we have adapted a model that forms a stable complex in a well between two barriers, and have investigated the self-diffusion of a hydrogen atom on a Cu(111) surface. In the former reaction, in addition to defining the complex channel, the cross-correlation function can avoid the oscillations seen in the ACFA. In the latter reaction, we introduce closed dividing surfaces that subdivide the potential energy surface for each channel. The combination of closed dividing surfaces and the CCFA provides well-defined rate constants for both single and multi-hopping rates.