title: Predicting cavity formation free energy: how far is the Gaussian approximation valid?
abstract: 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.
authors.affiliation: Department of Bioengineering, University of California, Berkeley, California 94720, USA.
authors.forename: T
authors.initials: T
authors.lastname: Head-Gordon
authors.forename: R M
authors.initials: RM
authors.lastname: Lynden-Bell
authors.forename: John R
authors.initials: JR
authors.lastname: Dowdle
authors.forename: P J
authors.initials: PJ
authors.lastname: Rossky