Tuesday, February 7, 2012

1202.1228 (Aljaz Godec et al.)

Physical origin underlying the entropy loss upon hydrophobic hydration    [PDF]

Aljaz Godec, Franci Merzel
The hydrophobic effect (HE) is commonly associated with the demixing of oil
and water at ambient conditions and plays the leading role in determining the
structure and stability of biomolecular assembly in aqueous solutions. On the
molecular scale HE has an entropic origin. It is believed that hydrophobic
particles induce order in the surrounding water by reducing the volume of con-
figuration space available for hydrogen bonding. Here we show with computer
simulation results that this traditional picture is not correct. Analyzing
collective fluctuations in water clusters we are able to provide a
fundamentally new picture of HE based on pronounced many-body correlations
affecting the switching of hydrogen bonds between molecules. These correlations
emerge as a non-local compensation of reduced fluctuations of local
electrostatic fields in the presence of an apolar solute.
View original: http://arxiv.org/abs/1202.1228

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