dorsal/arxiv
View SchemaAbsolute Hydration Free Energies of Ions, Ion-Water Clusters, and Quasi-chemical Theory
| Authors | D. Asthagiri, Lawrence R. Pratt, H. S. Ashbaugh |
|---|---|
| Categories | |
| ArXiv ID | physics/0303062 |
| URL | https://arxiv.org/abs/physics/0303062 |
| DOI | 10.1063/1.1587122 |
Abstract
Experimental studies on 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 on 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 on 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.
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"abstract": "Experimental studies on ion-water clusters have provided insights into the\nmicroscopic aspects of hydration phenomena. One common view is that extending\nthose experimental studies to larger cluster sizes would give the single ion\nabsolute hydration free energies not obtainable by classical thermodynamic\nmethods. This issue is reanalyzed in the context of recent computations and\nmolecular theories on ion hydration, particularly considering the hydration of\nH$^+$, Li$^+$, Na$^+$, and HO$^-$ ions and thence the hydration of neutral ion\npairs. The hydration free energies of neutral pairs computed here are in good\nagreement with experimental results, whereas the calculated absolute hydration\nfree energies, and the excess chemical potentials, deviate consistently from\nsome recently tabulated hydration free energies based on ion-water cluster\ndata. We show how the single ion absolute hydration free energies are not\nseparated from the potential of the phase in recent analyses of ion-water\ncluster data, even in the limit of large cluster sizes. We conclude that naive\ncalculations on ion-water clusters ought to agree with results obtained from\nexperimental studies of ion-water clusters because both values include the\ncontribution, somewhat extraneous to the local environment of the ion, from the\npotential of the phase.",
"arxiv_id": "physics/0303062",
"authors": [
"D. Asthagiri",
"Lawrence R. Pratt",
"H. S. Ashbaugh"
],
"categories": [
"physics.chem-ph",
"physics.bio-ph"
],
"doi": "10.1063/1.1587122",
"title": "Absolute Hydration Free Energies of Ions, Ion-Water Clusters, and Quasi-chemical Theory",
"url": "https://arxiv.org/abs/physics/0303062"
},
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