Winter Pierre, Richardson Jeremy O
Laboratory of Physical Chemistry , ETH Zürich , 8093 Zürich , Switzerland.
J Chem Theory Comput. 2019 May 14;15(5):2816-2825. doi: 10.1021/acs.jctc.8b01267. Epub 2019 Apr 2.
Ring-polymer instanton theory has been developed to simulate the quantum dynamics of molecular systems at low temperatures. Chemical reaction rates can be obtained by locating the dominant tunneling pathway and analyzing fluctuations around it. In the standard method, calculating the fluctuation terms involves the diagonalization of a large matrix, which can be unfeasible for large systems with a high number of ring-polymer beads. Here we present a method for computing the instanton fluctuations with a large reduction in computational scaling. This method is applied to three reactions described by fitted, analytic, and on-the-fly ab initio potential-energy surfaces and is shown to be numerically stable for the calculation of thermal reaction rates even at very low temperature.
环聚合物瞬子理论已被开发用于模拟低温下分子系统的量子动力学。通过定位主导隧穿路径并分析其周围的涨落，可以获得化学反应速率。在标准方法中，计算涨落项涉及一个大矩阵的对角化，这对于具有大量环聚合物珠子的大系统可能是不可行的。在这里，我们提出了一种计算瞬子涨落的方法，该方法在计算规模上有大幅缩减。该方法应用于由拟合、解析和实时从头算势能面描述的三个反应，并且即使在非常低的温度下，对于热反应速率的计算也显示出数值稳定性。
