Sumiya Yosuke, Taketsugu Tetsuya, Maeda Satoshi
Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita-ku, Sapporo, 060-8628, Japan.
Department of Chemistry, Faculty of Science, Hokkaido University, Kita-ku, Sapporo, 060-0810, Japan.
J Comput Chem. 2017 Jan 15;38(2):101-109. doi: 10.1002/jcc.24526. Epub 2016 Oct 31.
The branching ratio of unimolecular decomposition can be evaluated by solving the rate equations. Recent advances in automated reaction path search methods have enabled efficient construction of the rate equations based on quantum chemical calculations. However, it is still difficult to solve the rate equations composed of hundreds or more elementary steps. This problem is especially serious when elementary steps that occur in highly different timescales coexist. In this article, we introduce an efficient approach to obtain the branching ratio from a given set of rate equations. It has been derived from a recently proposed rate constant matrix contraction (RCMC) method, and termed full-RCMC (f-RCMC). The f-RCMC gives the branching ratio without solving the rate equations. Its performance was tested numerically for unimolecular decomposition of C H and C H . Branching ratios obtained by the f-RCMC precisely reproduced the values obtained by numerically solving the rate equations. It took about 95 h to solve the rate equations of C H consisting of 234 elementary steps. In contrast, the f-RCMC gave the branching ratio in less than 1 s. The f-RCMC would thus be an efficient alternative of the conventional kinetic simulation approach. © 2016 Wiley Periodicals, Inc.
单分子分解的分支比可通过求解速率方程来评估。自动反应路径搜索方法的最新进展使得基于量子化学计算高效构建速率方程成为可能。然而，求解由数百个或更多基元步骤组成的速率方程仍然很困难。当存在时间尺度差异极大的基元步骤共存时，这个问题尤为严重。在本文中，我们介绍了一种从给定的一组速率方程中获取分支比的有效方法。它源自最近提出的速率常数矩阵收缩（RCMC）方法，被称为全RCMC（f-RCMC）。f-RCMC无需求解速率方程就能给出分支比。我们对其性能进行了数值测试，用于CH和CH的单分子分解。通过f-RCMC获得的分支比精确再现了通过数值求解速率方程得到的值。求解由234个基元步骤组成的CH的速率方程大约需要95小时。相比之下，f-RCMC在不到1秒的时间内就给出了分支比。因此，f-RCMC将是传统动力学模拟方法的一种有效替代方法。© 2016威利期刊公司。
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