We present the results of atomistic molecular dynamics simulations with regard to specific ion effects in water, methanol and N,N-dimethylacetamide (DMAc). As a reference system, we introduce rigid and rod-like models of polyanions and polycations in combination with alkali metal cations and halide anions as counterions. Pronounced specific ion effects can be observed in terms of the individual anion and cation condensation behavior. The outcomes of our simulations thus reveal significant deviations from standard electrostatic mean-field theories. A detailed investigation of the individual energy contributions shows that ion–dipole interactions play a pivotal role in rationalizing the findings. The corresponding deviations in terms of the cation and anion distribution can be brought into agreement with the donor and acceptor numbers of the solvents, which thus highlights the importance of solvent–ion interactions in addition to electrostatic attraction.

中文翻译：

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水性和非水性介质中聚电解质的特定离子效应：离子溶剂化行为的重要性† ‡

我们介绍了有关水，甲醇和氮，氮中特定离子效应的原子分子动力学模拟的结果-二甲基乙酰胺（DMAc）。作为参考系统，我们引入了刚性和棒状的聚阴离子和聚阳离子模型，并结合了碱金属阳离子和卤化物阴离子作为抗衡离子。可以根据各个阴离子和阳离子的缩合行为观察到明显的特定离子效应。因此，我们的模拟结果显示出与标准静电均场理论的显着偏差。对单个能量贡献的详细研究表明，离子-偶极相互作用在合理化发现中起着关键作用。阳离子和阴离子分布方面的相应偏差可以与溶剂的供体和受体数量达成一致，因此，除了静电吸引之外，这突出了溶剂与离子相互作用的重要性。