Soft collective fluctuations governing hydrophobic association

Journal Article · Wed Sep 18 04:00:00 EDT 2013 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.111.127801· OSTI ID:1265936

Godec, Aljaz ^[1]; Smith, Jeremy C. ^[2]; Merzel, Franci ^[3]

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1. National Institute of Chemistry, Ljubljana (Slovenia); Univ. of Potsdam, Potsdam-Golm (Germany)
2. Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. National Institute of Chemistry, Ljubljana (Slovenia)

The interaction between two associating hydrophobic particles has traditionally been explained in terms of the release of entropically frustrated hydration shell water molecules. However, this picture cannot account for the kinetics of hydrophobic association and is therefore not capable of providing a microscopic description of the hydrophobic interaction (HI). Here, Monte Carlo simulations of a pair of molecular-scale apolar solutes in aqueous solution reveal the critical role of collective fluctuations in the hydrogen bond (HB) network for the microscopic picture of the HI. The main contribution to the HI is the relaxation of solute-water translational correlations. The existence of a heat capacity maximum at the desolvation barrier is shown to arise from softening of non-HB water fluctuations and the relaxation of many-body correlations in the labile HB network. Furthermore, the microscopic event governing the kinetics of hydrophobic association has turned out to be a relatively large critical collective fluctuation in hydration water displacing a substantial fraction of HB clusters from the inner to the outer region of the first hydration shell.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: ORNL Program Development; USDOE
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1265936
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 12 Vol. 111; ISSN 0031-9007
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
97 MATHEMATICS AND COMPUTING