Predicting cavity formation free energy: how far is the Gaussian approximation valid?

We examine the range of validity of the Gaussian model for various water-like liquids whose intermolecular potentials differ from SPC/E water, to provide insight into the temperature dependence of the hydrophobic effect for small hard sphere solutes. We find that low compressibility liquids that hav...

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Veröffentlicht in:Physical chemistry chemical physics : PCCP 2012-05, Vol.14 (19), p.6996-74
Hauptverfasser: Head-Gordon, T, Lynden-Bell, R. M, Dowdle, John R, Rossky, P. J
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Sprache:eng
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Zusammenfassung:We examine the range of validity of the Gaussian model for various water-like liquids whose intermolecular potentials differ from SPC/E water, to provide insight into the temperature dependence of the hydrophobic effect for small hard sphere solutes. We find that low compressibility liquids that have more close-packed network structures show much larger deviations from Gaussian fluctuations for low or zero occupancies relative to more compressible fluids with more open networks. Water appears to be a unique molecular fluid in possessing equilibrium density fluctuations that are faithfully described by the Gaussian theory. We ascribe this success to the fact, shown here, that the orientational correlations near a small hard sphere solute involve remarkably little reorganization from the bulk, which is a consequence of water's low solvent reorganization enthalpy and entropy. We examine the range of validity of the Gaussian model for various water-like liquids whose intermolecular potentials differ from SPC/E water, to provide insight into the temperature dependence of the hydrophobic effect for small hard sphere solutes.
ISSN:1463-9076
1463-9084
DOI:10.1039/c2cp00046f