Institut für Computerphysik, Universität Stuttgart, Allmandring 3, D-70569 Stuttgart, Germany.
J Chem Phys. 2018 Oct 28;149(16):163319. doi: 10.1063/1.5028354.
We present a new polarizable coarse-grained martini force field for monovalent ions, called refIon, which is developed mainly for the accurate reproduction of electrostatic properties in aqueous electrolyte solutions. The ion model relies on full long-range Coulomb interactions and introduces satellite charges around the central interaction site in order to model molecular polarization effects. All force field parameters are matched to reproduce the mass density and the static dielectric permittivity of aqueous NaCl solutions, such that experimental values are well-reproduced up to moderate salt concentrations of . In addition, an improved agreement with experimentally measured ionic conductivities is observed. Our model is validated with regard to analytic solutions for the ion distribution around highly charged rod-like polyelectrolytes in combination with atomistic simulations and experimental results concerning structural properties of lipid bilayers in the presence of distinct salt concentrations. Further results regarding the coordination numbers of counterions around dilute poly(styrene sulfonate) and poly(diallyldimethylammonium) polyelectrolyte chains also highlight the applicability of our approach. The introduction of our force field allows us to eliminate heuristic scaling factors, as reported for previous martini ion models in terms of effective salt concentrations, and in consequence provides a better agreement between simulation and experimental results. The presented approach is specifically useful for recent martini attempts that focus on highly charged systems-such as models of DNA, polyelectrolytes or polyelectrolyte complexes-where precise studies of electrostatic effects and charge transport processes are essential.
我们提出了一种新的可极化的粗粒马蒂尼离子力场，称为 refIon，它主要是为了准确再现水相电解质溶液中的静电特性而开发的。该离子模型依赖于全远程库仑相互作用，并在中心相互作用位点周围引入卫星电荷，以模拟分子极化效应。所有力场参数都经过匹配，以再现水合 NaCl 溶液的质量密度和静态介电常数，从而在中等盐浓度下很好地再现实验值。此外，还观察到与实验测量的离子电导率的改善一致性。我们的模型通过与原子模拟相结合的高电荷棒状聚电解质周围的离子分布的解析解以及关于不同盐浓度下脂质双层结构性质的实验结果进行了验证。关于稀聚（苯乙烯磺酸盐）和聚（二烯丙基二甲基氯化铵）聚电解质链周围抗衡离子配位数的进一步结果也突出了我们方法的适用性。我们的力场的引入使得能够消除启发式缩放因子，如先前的马蒂尼离子模型中关于有效盐浓度的报告，从而在模拟和实验结果之间提供更好的一致性。该方法特别适用于最近的马蒂尼尝试，这些尝试侧重于高电荷系统，如 DNA、聚电解质或聚电解质复合物模型，在这些系统中，静电效应和电荷传输过程的精确研究至关重要。
