Ishida Tateki
Department of Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.
J Phys Chem B. 2005 Oct 6;109(39):18558-64. doi: 10.1021/jp052268o.
A polarizable solute model, based on the empirical valence bond approach, is developed and applied to electron transfer (ET) reactions in polarizable and flexible water solvents. The polarization effect is investigated in comparison with a nonpolarizable solute and solvent model. With free energy curves constructed by a molecular dynamics simulation, the activation energy barrier and the reorganization energy related to ET processes are investigated. The present simulation results show that the activation energy barrier becomes larger in the polarizable model than in the nonpolarizable model and that this makes the ET rate slower than that with the nonpolarizable model. It is shown that the effect of the electronic energy difference of solute molecule on free energy profiles is remarkable and that, corresponding to this effect, the reorganization energy is significantly modified. These results indicate that the process of solvent polarization by the polarized solute to enhance the solute-solvent interaction is a key factor and that treating the polarization of both solute and solvent at the same time is essential. Also, the polarization effect on the diffusive motion of the solute molecule in the polarization solvent is studied. The polarized solute molecule shows slower diffusive motion compared with that in the nonpolarizable model.
基于经验价键方法开发了一种可极化溶质模型，并将其应用于可极化且灵活的水溶剂中的电子转移（ET）反应。与不可极化的溶质和溶剂模型相比，研究了极化效应。通过分子动力学模拟构建自由能曲线，研究了与ET过程相关的活化能垒和重组能。目前的模拟结果表明，可极化模型中的活化能垒比不可极化模型中的更大，这使得ET速率比不可极化模型中的更慢。结果表明，溶质分子的电子能量差对自由能分布的影响显著，并且相应于此效应，重组能被显著改变。这些结果表明，极化溶质使溶剂极化以增强溶质 - 溶剂相互作用的过程是一个关键因素，同时处理溶质和溶剂的极化至关重要。此外，还研究了极化对溶质分子在极化溶剂中扩散运动的影响。与不可极化模型相比，极化溶质分子表现出较慢的扩散运动。
