Charge hydration asymmetry: the basic principle and how to use it to test and improve water models.
Charge hydration asymmetry: the basic principle and how to use it to test and improve water models.
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DOI：
10.1021/jp305226j
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发表时间：
2012-08-16
影响因子：
3.3
通讯作者：
Onufriev, Alexey V.
中科院分区：
文献类型：
--
作者：
Mukhopadhyay, Abhishek;Fenley, Andrew T.;Tolokh, Igor S.;Onufriev, Alexey V.
电荷水化不对称（CHA）表现为离子水化的自由能对离子电荷符号的强烈依赖。这种不对称性并没有被普遍的溶剂化模型一致地解释；它的大小在不同的模型之间差别很大。虽然很清楚CHA在某种程度上与水分子内的电荷分布有关，但这种关系的确切性质尚不清楚。我们提出了一个简单，但一般和严格的标准，将水分子电荷分布的旋转和电荷反转性质与其引起CHA的能力联系起来。我们展示了水分子的哪些电多极组分是解释其不对称电荷水化能力的关键。然后，我们测试了几种流行的水模型，并解释了为什么特定模型在模拟中显示没有、很少或很强的CHA。我们利用获得的洞察力推导出波恩方程的模拟，该方程包括解释CHA所需的缺失物理，并且不依赖于重新定义连续介质边界。该公式与原公式一样简单，不含任何拟合参数，能在实验不确定度范围内预测球形阳离子和阴离子的水化自由能和熵。我们的研究结果表明，通过明确地将CHA引入现有的连续介质框架，可以大大减少实际连续介质静电框架与更基本的明确溶剂处理之间的差距。
Charge hydration asymmetry (CHA) manifests itself in the experimentally observed strong dependence of free energy of ion hydration on the sign of the ion charge. This asymmetry is not consistently accounted for by popular models of solvation; its magnitude varies greatly between the models. While it is clear that CHA is somehow related to charge distribution within a water molecule, the exact nature of this relationship is unknown. We propose a simple, yet general and rigorous criterion that relates rotational and charge inversion properties of a water molecule’s charge distribution with its ability to cause CHA. We show which electric multipole components of a water molecule are key to explain its ability for asymmetric charge hydration. We then test several popular water models and explain why specific models show none, little, or strong CHA in simulations. We use the gained insight to derive an analogue of the Born equation that includes the missing physics necessary to account for CHA, and does not rely on re-defining the continuum dielectric boundary. The proposed formula is as simple as the original, does not contain any fitting parameters, and predicts hydration free energies and entropies of spherical cations and anions within experimental uncertainty. Our findings suggest that the gap between the practical continuum electrostatics framework and the more fundamental explicit solvent treatment may be reduced considerably by explicitly introducing CHA into the existing continuum framework.
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DOI：
10.1021/jp809782z
发表时间：
2009-05-14
期刊：
The journal of physical chemistry. B
影响因子：
--
作者：
Fennell CJ;Bizjak A;Vlachy V;Dill KA
通讯作者：
Dill KA
影响因子：
4.4
作者：
Dzubiella, J;Hansen, JP
通讯作者：
Hansen, JP
影响因子：
5.5
作者：
Corbeil, Christopher R.;Sulea, Traian;Purisima, Enrico O.
通讯作者：
Purisima, Enrico O.
影响因子：
4.4
作者：
Grossfield, A
通讯作者：
Grossfield, A
影响因子：
2.8
作者：
Gladich, Ivan;Shepson, Paul;Carignano, Marcelo
通讯作者：
Carignano, Marcelo