A microscopic theory for solution chemical reactions : introduction of reactant and medium structures into generalized Langevin equation formalism
A microscopic theory for solution chemical reactions : introduction of reactant and medium structures into generalized Langevin equation formalism
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溶液化学反应的微观理论：将反应物和介质结构引入广义朗之万方程形式
DOI：
10.1002/qua.560510617
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发表时间：
1994
影响因子：
2.2
通讯作者：
T. Yamabe
中科院分区：
文献类型：
--
作者：
M. Nagaoka;Y. Okuno;Naoto Yoshida;T. Yamabe
本文在最近量子化学方法所获得的微观理解的基础上，提出了一种考虑反应物和介质结构的溶液化学反应的微观公式（即，从头算分子轨道理论等）。假设热平衡的介质浴，推导出一个有效的内部哈密顿量，并进一步证明，其导数相对于内部正常坐标明确给出相同的力场所提供的自由能表面或潜在的平均力。自由能表面可以在复合正常坐标系（CNCS）中表示，该复合正常坐标系由孤立的反应物和周围溶剂分子的一些正常坐标系组成（即，中等溶剂分子）。在CNCS中，在使用的对角元素中获得的自由能表面的海森矩阵，有效的正常模式的频率，这反映了平衡溶剂的效果，估计。此外，广义朗之万方程（GLE）的处理，封闭的表达式的时间依赖性的摩擦系数推导出微观的基础上，反映反应物和溶剂的结构。非平衡效应估计的解析表达式类似于在Grote-Hynes理论。速率常数进行了评估，为一个典型的模型系统，它表明，平衡速率常数应减少了0.997倍。最后得出结论，目前的微观理论是合理的适用于溶液中的化学反应速率常数的估计。John Wiley & Sons，Inc.
A microscopic formulation of solution chemical reactions, taking reactants and medium structures into consideration, is presented on the basis of microscopic understandings obtained by recent quantum chemical methods (i.e., ab initio molecular orbital theory, etc.). Assuming thermal equilibrium of the medium bath, an effective internal Hamiltonian is derived, and, further, its derivative with respect to internal normal coordinates is proved explicitly to give the same force field as is provided by the free-energy surface or potential of mean force. The free-energy surface can be expressed in the composite normal coordinate system (CNCS) consisting of some normal coordinate systems of isolated reactants and surrounding solvent molecules (i.e., medium solvent molecules). In CNCS, in use of diagonal elements obtained in the Hessian matrix of the free-energy surface, effective normal-mode frequencies, which reflect the equilibrium solvent effect, are estimated. Furthermore, on the generalized Langevin equation (GLE) treatment, a closed expression of the time-dependent frictional coefficient is derived on a microscopic basis, reflecting the reactant and solvent structures. The nonequilibrium effect is estimated by an analytical expression similar to that in the Grote–Hynes theory. The rate constant is evaluated for a typical model system and it is shown that the equilibrium rate constants should be reduced by a factor 0.997. Finally, it is concluded that the present microscopic theory is reasonably applicable to the estimation of chemical reaction rate constants in solution. © 1994 John Wiley & Sons, Inc.