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首页> 外文期刊>The Journal of Chemical Physics >The short range anion-H interaction is the driving force for crystal formation of ions in water
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The short range anion-H interaction is the driving force for crystal formation of ions in water

机译：短程阴离子-H相互作用是水中离子晶体形成的驱动力

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The crystal formation of NaCl in water is studied by extensive molecular dynamics simulations. Ionic solutions at room temperature and various concentrations are studied using the SPC/E and TIP4P/2005 water models and seven force fields of NaCl. Most force fields of pure NaCl fail to reproduce the experimental density of the crystal, and in solution some favor dissociation at saturated conditions, while others favor crystal formation at low concentration. A new force field of NaCl is proposed, which reproduces the experimental phase diagram in the solid, liquid, and vapor regions. This force field overestimates the solubility of NaCl in water at saturation conditions when used with standard Lorentz–Berthelot combining rules for the ion-water pair potentials. It is shown that precipitation of ions is driven by the short range interaction between Cl–H pairs, a term which is generally missing in the simulation of ionic solutions. The effects of intramolecular flexibility of water on the solubility of NaCl ions are analyzed and is found to be small compared to rigid models. A flexible water model, extending the rigid SPC/E, is proposed, which incorporates Lennard-Jones interactions centered on the hydrogen atoms. This force field gives liquid-vapor coexisting densities and surface tensions in better agreement with experimental data than the rigid SPC/E model. The Cl–H, Na–O, and Cl–O pair distribution functions of the rigid and flexible models agree well with experiment. The predicted concentration dependence of the electric conductivity is in fair agreement with available experimental data.
机译：通过广泛的分子动力学模拟研究了NaCl在水中的晶体形成。使用SPC / E和TIP4P / 2005水模型以及NaCl的七个力场研究了室温和各种浓度的离子溶液。纯NaCl的大多数力场无法重现晶体的实验密度，在溶液中，有些有利于在饱和条件下解离，而另一些有利于低浓度下的晶体形成。提出了一种新的NaCl力场，该力场再现了固体，液体和蒸气区域的实验相图。当与标准Lorentz-Berthelot结合离子水对电位的规则结合使用时，此力场会高估饱和条件下NaCl在水中的溶解度。结果表明，离子的沉淀是由Cl–H对之间的短程相互作用驱动的，该术语通常在离子溶液的模拟中不存在。分析了水的分子内柔性对NaCl离子溶解度的影响，发现与刚性模型相比，该影响较小。提出了扩展刚性SPC / E的灵活水模型，该模型合并了以氢原子为中心的Lennard-Jones相互作用。与刚性SPC / E模型相比，该力场提供了液体-蒸汽共存的密度和表面张力，与实验数据更加吻合。刚性和柔性模型的Cl–H，Na–O和Cl–O对分布函数与实验吻合良好。预测的电导率浓度依赖性与可用的实验数据完全一致。

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