Transferable ionic parameters for first-principles Poisson-Boltzmann solvation calculations: Neutral solutes in aqueous monovalent salt solutions.
Transferable ionic parameters for first-principles Poisson-Boltzmann solvation calculations: Neutral solutes in aqueous monovalent salt solutions.
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DOI：
10.1063/1.4978850
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发表时间：
2017-04
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通讯作者：
Stefan Ringe;H. Oberhofer;K. Reuter
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作者：
Stefan Ringe;H. Oberhofer;K. Reuter
基于Stern层修正尺寸修正Poisson-Boltzmann（SMPB）模型的隐式溶剂化计算是第一性原理电子结构计算中捕捉电解质效应的有效方法。对于给定的盐溶液，它们需要一系列离子特异性参数，这些参数描述了溶解离子的大小以及Stern层的厚度和形状。在这个定义的参数空间，我们表明，斯特恩层厚度表示的溶质的电子密度和由此产生的离子腔体积完全确定离子的影响，中性溶质的稳定性。使用有效的SMPB功能的全电位密度泛函理论包FHI的目标，我们得到优化的中性溶质在各种水性一价电解质的斯特恩层参数。参数化方案依赖于拟合参考Setschenow系数，该系数描述了溶剂化自由能随低至中等浓度下离子强度的变化。NaCl溶液的这些数据的可用性产生了高度预测的SMPB模型，该模型允许以与流行的定量回归模型相当的精度恢复测量的Setschenow系数。相应地衍生的SMPB参数的其他盐遭受一个更稀缺的实验数据库，但导致斯特恩层的属性，遵循物理上合理的趋势与离子水合数。
Implicit solvation calculations based on a Stern-layer corrected size-modified Poisson-Boltzmann (SMPB) model are an effective approach to capture electrolytic effects in first-principles electronic structure calculations. For a given salt solution, they require a range of ion-specific parameters, which describe the size of the dissolved ions as well as thickness and shape of the Stern layer. Out of this defined parameter space, we show that the Stern layer thickness expressed in terms of the solute's electron density and the resulting ionic cavity volume completely determine ion effects on the stability of neutral solutes. Using the efficient SMPB functionality of the full-potential density-functional theory package FHI-aims, we derive optimized such Stern layer parameters for neutral solutes in various aqueous monovalent electrolytes. The parametrization protocol relies on fitting to reference Setschenow coefficients that describe solvation free energy changes with ionic strength at low to medium concentrations. The availability of such data for NaCl solutions yields a highly predictive SMPB model that allows to recover the measured Setschenow coefficients with an accuracy that is comparable to prevalent quantitative regression models. Correspondingly derived SMPB parameters for other salts suffer from a much scarcer experimental data base but lead to Stern layer properties that follow a physically reasonable trend with ionic hydration numbers.