Many catalytic and biomolecular reactions containing transition metals involve changes in the electronic spin state. These processes are referred to as “spin‐forbidden” reactions within nonrelativistic quantum mechanics framework. To understand detailed reaction mechanisms of spin‐forbidden reactions, one must characterize reaction pathways on potential energy surfaces with different spin states and then identify crossing points. Here we propose a practical computational scheme, where only the lowest mixed‐spin eigenstate obtained from the diagonalization of the spin‐coupled Hamiltonian matrix is used in reaction path search calculations. We applied this method to the 6,4FeO+ + H2 → 6,4Fe+ + H2O, 6,4FeO+ + CH4 → 6,4Fe+ + CH3OH, and 7Mn+ + OCS → 5MnS+ + CO reactions, for which crossings between the different spin states are known to play essential roles in the overall reaction kinetics. © 2018 Wiley Periodicals, Inc.

中文翻译：

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自动反应路径搜索自旋禁止反应

许多含有过渡金属的催化和生物分子反应涉及电子自旋状态的变化。这些过程在非相对论量子力学框架内被称为“自旋禁止”反应。要了解自旋禁止反应的详细反应机制，必须表征具有不同自旋态的势能表面上的反应途径，然后确定交叉点。在这里，我们提出了一种实用的计算方案，其中仅从自旋耦合哈密顿矩阵的对角化中获得的最低混合自旋本征态用于反应路径搜索计算。我们将此方法应用于 6,4FeO+ + H2 → 6,4Fe+ + H2O、6,4FeO+ + CH4 → 6,4Fe+ + CH3OH 和 7Mn+ + OCS → 5MnS+ + CO 反应，已知不同自旋状态之间的交叉在整个反应动力学中起着至关重要的作用。© 2018 Wiley Periodicals, Inc.