Laboratory for Waste Management, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
Phys Chem Chem Phys. 2012 Aug 7;14(29):10248-57. doi: 10.1039/c2cp40711f. Epub 2012 Jun 25.
We assessed the relative merits of two approaches for including polarization effects in classical force fields for the sulfate anion. One of the approaches is the explicit shell model for atomic polarization and the other is an implicit dielectric continuum representation of the electronic polarization, wherein the polarizability density is spatially uniform. Both the solvation and ion association properties of sulfate were considered. We carried out an ab initio molecular dynamics simulation for a single sulfate anion in aqueous solution to obtain a benchmark for the solvation structure. For the ion-pairing properties, the models were compared to experimental thermodynamic data through Kirkwood-Buff theory, which relates the integrals of the pair correlation functions to measurable properties. While deficiencies were found for both of the approaches, the continuum polarization model was not systematically worse than the shell model. The shell model was found to give a more structured solution than the continuum polarization model, both with respect to solvation and ion pairing.
我们评估了在硫酸盐阴离子的经典力场中纳入极化效应的两种方法的相对优点。一种方法是原子极化的显式壳模型，另一种方法是电子极化的隐含介电连续体表示，其中极化率密度是空间均匀的。我们考虑了硫酸盐的溶剂化和离子缔合性质。我们进行了单硫酸盐阴离子在水溶液中的从头算分子动力学模拟，以获得溶剂化结构的基准。对于离子配对性质，通过 Kirkwood-Buff 理论将模型与实验热力学数据进行了比较，该理论将对关联函数的积分与可测量的性质联系起来。虽然两种方法都存在缺陷，但连续极化模型并不比壳模型系统地差。壳模型被发现比连续极化模型更能给出结构化的溶液，无论是在溶剂化还是离子配对方面。
