Chemical oxidation reactions, a key class of electron transfer processes, have broad applications, including the treatment of persistent and mobile pollutants. Marcus theory, paired with density functional theory (DFT) simulations, enables quantification of thermodynamic properties in these reactions. However, accurately modeling species with complex solvent interactions, especially radicals, requires careful selection of computational methods. Reduction potentials provide critical benchmarks for evaluating solvent models and functional choices by comparing simulated values to literature data. In this study, we used the carbonate radical, known for its strong intermolecular interactions, as a model to assess solvation models and computational functionals. Implicit solvation methods significantly underperformed, predicting only one-third of the measured reduction potential. Accurate results were obtained using explicit solvation with 18 water molecules for ωB97xD/6-311++G(2d,2p) and 9 water molecules for M06-2X/6-311++G(2d,2p). B3LYP/6-311++G(2d,2p) showed improvement with additional explicit solvation but failed to match literature benchmarks. Functional performance differences, analyzed through natural bond orbital (NBO) and charge transfer calculations, emphasized the critical role of dispersion corrections. Testing various dispersion correction methods revealed consistent improvements in reduction potential accuracy. These findings highlight the necessity of explicit solvation for modeling electron transfer reactions with extensive solvent interactions and underscore the importance of selecting appropriate functionals and dispersion corrections for reliable predictions.

中文翻译：

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显式溶剂化作用和理论水平对 DFT 预测碳酸盐自由基阴离子水还原电位的作用


化学氧化反应是电子转移过程的一个关键类别，具有广泛的应用，包括处理持久性和移动污染物。Marcus 理论与密度泛函理论 （DFT） 仿真相结合，能够量化这些反应中的热力学特性。然而，要准确模拟具有复杂溶剂相互作用的物质，尤其是自由基，需要仔细选择计算方法。通过将模拟值与文献数据进行比较，还原电位为评估溶剂模型和功能选择提供了关键基准。在这项研究中，我们使用以其强大的分子间相互作用而闻名的碳酸盐自由基作为模型来评估溶剂化模型和计算泛函。隐式溶剂化方法明显表现不佳，仅预测了测得的还原电位的三分之一。使用 ωB97xD/6-311++G（2d，2p） 的 18 个水分子和 M06-2X/6-311++G（2d，2p） 的 9 个水分子进行显式溶剂化，获得准确的结果。B3LYP/6-311++G（2d，2p） 在额外的显式溶剂化后表现出改善，但未能与文献基准相匹配。通过自然键轨道 （NBO） 和电荷转移计算分析功能性能差异，强调了色散校正的关键作用。测试各种色散校正方法表明，还原电位准确性的持续提高。这些发现强调了显式溶剂化对具有广泛溶剂相互作用的电子转移反应进行建模的必要性，并强调了选择合适的泛函和分散校正对于可靠预测的重要性。