Molecular dynamics study of hydration in ethanol-water mixtures using a polarizable force field
Molecular dynamics study of hydration in ethanol-water mixtures using a polarizable force field
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DOI：
10.1021/jp045438q
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发表时间：
2005-04-14
影响因子：
3.3
通讯作者：
Roux, B
中科院分区：
文献类型：
--
作者：
Noskov, SY;Lamoureux, G;Roux, B
水相中乙醇溶剂化的异常物理化学特性通常归因于疏水水合现象。为了研究水 - 乙醇混合物中疏水水合的结构组织，我们使用基于详细原子模型的分子动力学模拟。基于经典的德鲁德振子模型，将诱导极化纳入势函数。在11种乙醇摩尔分数（从0.05到0.9）下对水 - 乙醇混合物进行模拟。尽管水和乙醇模型是分别参数化的，以重现环境条件下纯液体的汽化焓、静态介电常数和自扩散常数，但它们也能准确地重现混合物的能量和动力学性质。此外，各种水 - 醇混合物计算得到的介电常数与实验数据高度吻合。模拟提供了混合物详细的结构特征。乙醇第一水合层中水分子间氢键的减少由第二水合层的增强所补偿。对于乙醇摩尔分数高达约等于0.5时，第二溶剂化层的结构化效应导致净正氢键过量。对于更大的摩尔分数，第二水合层的填充不足以克服第一水合层中净氢键的减少。
The abnormal physicochemical characteristics of ethanol solvation in water are commonly attributed to the phenomenon of hydrophobic hydration. To investigate the structural organization of hydrophobic hydration in water-ethanol mixtures, we use molecular dynamics simulations based on detailed atomic models. Induced polarization is incorporated into the potential function on the basis of the classical Drude oscillator model. Water-ethanol mixtures are simulated at 11 ethanol molar fractions, from 0.05 to 0.9. Although the water and ethanol models are parametrized separately to reproduce the vaporization enthalpy, static dielectric constant, and self-diffusion constant of neat liquids at ambient conditions, they also reproduce the energetic and dynamical properties of the mixtures accurately. Furthermore, the calculated dielectric constant for the various wateralcohol mixtures is in excellent agreement with experimental data. The simulations provide a detailed structural characterization of the mixtures. A depletion of water-water hydrogen bonding in the first hydration shell of ethanol is compensated by an enhancement in the second hydration shell. The structuring effect from the second solvation shell gives rise to a net positive hydrogen-bonding excess for ethanol molar fractions up to similar or equal to 0.5. For larger molar fractions, the second hydration shell is not sufficiently populated to overcome the net H-bond depletion from the first shell.