Quantifying Uncertainties in Solvation Procedures for Modeling Aqueous Phase Reaction Mechanisms
Quantifying Uncertainties in Solvation Procedures for Modeling Aqueous Phase Reaction Mechanisms
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DOI：
10.1021/acs.jpca.0c08961
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发表时间：
2021-01-04
影响因子：
2.9
通讯作者：
Keith, John A.
中科院分区：
文献类型：
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作者：
Maldonado, Alex M.;Hagiwara, Satoshi;Keith, John A.
计算量子化学为许多化学领域的溶剂化反应机制提供了基本的化学和物理见解，特别是在均相和多相可再生能源催化方面。这种反应可能依赖于与离子和溶剂分子的明确相互作用，而这些相互作用是不容易表征的。用分子动力学严格模拟显式溶剂效应通常会带来高昂的计算成本，而连续介质模型的性能，如极化连续介质模型（PCM）、电荷不对称非局部确定的局部电（CANDLE）、真实溶剂的类导体筛选模型（cosmos - rs）和参考相互作用位点模型（ESM-RISM）的有效筛选介质方法，对反应机理的了解较少。在这里，我们重新审视了一个基本的水氢化物转移反应——硼氢化钠（NaBH4）还原二氧化碳（CO2）——作为一个测试案例，以评估不同溶剂模型在与可再生能源催化机制相关的水相电荷迁移中的表现。对于该体系，量子力学/分子力学（QM/MM）分子动力学模拟几乎完全再现了QM模拟的能量分布，QM/MM模拟中的Na+反离子对描述反应路径的系综平均轨迹的影响不显著。然而，在静态计算中使用的溶剂模型在数据上有更多的可变性，这取决于系统是否使用显式溶剂壳和/或反相来建模。我们指出这种可变性是由于气相中电荷分离状态的非物理描述（即自相互作用误差），并且我们表明使用更精确的杂化泛函和/或明确的溶剂壳层可以减少这些误差。这项工作结束了在未来研究可再生能源催化机制的计算工作中处理溶剂化的推荐程序。
Computational quantum chemistry provides fundamental chemical and physical insights into solvated reaction mechanisms across many areas of chemistry, especially in homogeneous and heterogeneous renewable energy catalysis. Such reactions may depend on explicit interactions with ions and solvent molecules that are nontrivial to characterize. Rigorously modeling explicit solvent effects with molecular dynamics usually brings steep computational costs while the performance of continuum solvent models such as polarizable continuum model (PCM), charge-asymmetric nonlocally determined local-electric (CANDLE), conductor-like screening model for real solvents (COSMO-RS), and effective screening medium method with the reference interaction site model (ESM-RISM) are less well understood for reaction mechanisms. Here, we revisit a fundamental aqueous hydride transfer reaction-carbon dioxide (CO2) reduction by sodium borohydride (NaBH4)-as a test case to evaluate how different solvent models perform in aqueous phase charge migrations that would be relevant to renewable energy catalysis mechanisms. For this system, quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations almost exactly reproduced energy profiles from QM simulations, and the Na+ counterion in the QM/MM simulations plays an insignificant role over ensemble averaged trajectories that describe the reaction pathway. However, solvent models used on static calculations gave much more variability in data depending on whether the system was modeled using explicit solvent shells and/or the counterion. We pinpoint this variability due to unphysical descriptions of charge-separated states in the gas phase (i.e., self-interaction errors), and we show that using more accurate hybrid functionals and/or explicit solvent shells lessens these errors. This work closes with recommended procedures for treating solvation in future computational efforts in studying renewable energy catalysis mechanisms.