Absolute hydration free energies of ions, ion-water clusters, and quasichemical theory
Absolute hydration free energies of ions, ion-water clusters, and quasichemical theory
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DOI：
10.1063/1.1587122
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发表时间：
2003-08-01
影响因子：
4.4
通讯作者：
Ashbaugh, HS
中科院分区：
文献类型：
--
作者：
Asthagiri, D;Pratt, LR;Ashbaugh, HS
离子-水团簇的实验研究为水化现象的微观方面提供了见解。一种普遍的观点是，将这些实验研究扩展到更大的簇大小，将得到单离子的绝对水合自由能，这是经典热力学方法无法获得的。这个问题在最近的计算和离子水合的分子理论的背景下重新分析，特别是考虑到H+， Li+， Na+和HO-离子的水合作用，以及由此产生的中性离子对的水合作用。本文计算的中性对的水化自由能与实验结果吻合较好，而计算的绝对水化自由能和过量化学势与最近根据离子-水簇数据制表的水化自由能存在一致的偏差。我们展示了在最近的离子-水簇数据分析中，即使在大簇尺寸的限制下，单离子的绝对水合自由能如何不与相的势分离。我们的结论是，离子-水团簇的初始计算应该与离子-水团簇的实验研究结果一致，因为两个值都包括了相电位的贡献，这与离子的局部环境有些无关。(C) 2003年美国物理研究所。
Experimental studies of ion-water clusters have provided insights into the microscopic aspects of hydration phenomena. One common view is that extending those experimental studies to larger cluster sizes would give the single-ion absolute hydration free energies not obtainable by classical thermodynamic methods. This issue is reanalyzed in the context of recent computations and molecular theories of ion hydration, particularly considering the hydration of H+, Li+, Na+, and HO- ions, and thence the hydration of neutral ion pairs. The hydration free energies of neutral pairs computed here are in good agreement with experimental results, whereas the calculated absolute hydration free energies and the excess chemical potentials deviate consistently from some recently tabulated hydration free energies based on ion-water cluster data. We show how the single-ion absolute hydration free energies are not separated from the potential of the phase in recent analyses of ion-water cluster data, even in the limit of large cluster sizes. We conclude that naive calculations of ion-water clusters ought to agree with results obtained from experimental studies of ion-water clusters because both values include the contribution, somewhat extraneous to the local environment of the ion, from the potential of the phase. (C) 2003 American Institute of Physics.