Computational assessment of the entropy of solvation of small-sized hydrophobic entities

Mahajan, R.; Höfinger, S.; Hansmann, U. H. E.; Volkert, J.; Kranzlmüller, D.

doi:10.1039/b611200e

Journal Article

PreJuSER-54180

Computational assessment of the entropy of solvation of small-sized hydrophobic entities

Mahajan, R. ; Kranzlmüller, D. ; Volkert, J. ; Hansmann, U. H. E.FZJ* ; Höfinger, S.

2006
RSC Publ. Cambridge

Physical Chemistry Chemical Physics 8, 5515 (2006) [10.1039/b611200e]

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Please use a persistent id in citations: http://hdl.handle.net/2128/2372 doi:10.1039/b611200e

Abstract: A high level polarizable force field is used to study the temperature dependence of hydrophobic hydration of small-sized molecules from computer simulations. Molecular dynamics (MD) simulations of liquid water at various temperatures form the basis of free energy perturbation calculations that consider the onset and growth of a repulsive sphere. This repulsive sphere acts as a model construct for the hydrophobic species. In the present study, an extension is pursued for seven independent target temperatures, ranging from close to the freezing point almost up to the boiling point of liquid water under standard conditions. Care is taken to maintain proper physico-chemical model descriptions by cross-checking with experimental water densities at the selected target temperatures. The polarizable force field description of molecular water turns out to be suitable throughout the entire temperature domain considered. Derivatives of the computed free energies of hydrophobic hydration with respect to the temperature give access to the changes in entropy. In practice the entropy differential is determined from the negative of the slope of tangential lines formed at a certain target temperature in the free energy profile. The obtained changes in entropy are negative for small-sized cavities, and hence reconfirm the basic ideas of the Lum-Chandler-Weeks theory on hydrophobic hydration of small-sized solutes.

Keyword(s): Computer Simulation (MeSH) ; Entropy (MeSH) ; Evaluation Studies as Topic (MeSH) ; Hydrophobic and Hydrophilic Interactions (MeSH) ; Temperature (MeSH) ; Thermodynamics (MeSH) ; Water (MeSH) ; Water ; J