Magnesium and zinc dications possess the same charge and have an almost identical size, yet they behave very differently in aqueous solutions and play distinct biological roles. It is thus crucial to identify the origins of such different behaviors and to assess to what extent they can be captured by force-field molecular dynamics simulations. In this work, we combine neutron scattering experiments in a specific mixture of H₂O and D₂O (the so-called null water) with ab initio molecular dynamics simulations to probe the difference in the hydration structure and ion-pairing properties of chloride solutions of the two cations. The obtained data are used as a benchmark to develop a scaled-charge force field for Mg²⁺ that includes electronic polarization in a mean field way. We show that using this electronic continuum correction we can describe aqueous magnesium chloride solutions well. However, in aqueous zinc chloride specific interaction terms between the ions need to be introduced to capture ion pairing quantitatively.

中文翻译：

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Mg ²⁺和Zn ²⁺水溶液中的水合和离子配对：中子散射实验和从头算分子动力学模拟的力场描述

镁和锌指示剂具有相同的电荷，大小几乎相同，但它们在水溶液中的行为却大不相同，并发挥不同的生物学作用。因此，至关重要的是要确定这种不同行为的起源，并评估它们在多大程度上可以通过力场分子动力学模拟捕获。在这项工作中，我们将在H ₂ O和D ₂ O（所谓的无效水）的特定混合物中的中子散射实验与从头算分子动力学模拟相结合，以探讨氯化物的水合结构和离子对性质的差异。两个阳离子的溶液。获得的数据用作开发Mg ^2+的标称电荷力场的基准其中包括以平均场方式进行的电子极化。我们表明，使用这种电子连续校正可以很好地描述氯化镁水溶液。但是，在氯化锌水溶液中，需要引入离子之间的特定相互作用项以定量捕获离子对。