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Updated: Jun 27, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Static and dynamic correlations in water at hydrophobic interfaces
Jeetain Mittal1, Gerhard Hummer
1Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0520, USA.
Summary
Large nonpolar solutes broaden water interfaces via capillary waves. These fluctuations create dynamic wet/dry regions, mimicking a free liquid-vapor interface behavior.
Area of Science:
- Physical Chemistry
- Soft Matter Physics
- Computational Biophysics
Background:
- Understanding water interfaces is crucial for solvation phenomena.
- The behavior of water near nonpolar solutes is complex and not fully understood.
- Capillary wave theory describes interfaces of liquids but its applicability to solute-water interfaces needs investigation.
Purpose of the Study:
- To investigate the static and dynamic properties of water-density fluctuations at interfaces with large nonpolar solutes.
- To determine the influence of solute size on interfacial properties.
- To compare the behavior of water interfaces near solutes with free liquid-vapor interfaces.
Main Methods:
- Extensive molecular dynamics simulations using TIP4P water model.
- Simulations focused on smooth spherical solutes of varying sizes.
- Analysis of interfacial density profiles and local density fluctuations.
Main Results:
- Interfacial density profiles are broadened by capillary waves for large solutes.
- The interface width scales logarithmically with solute size, consistent with capillary-wave theory.
- Apparent interfacial tension and fluctuation correlation lengths match those of a free liquid-vapor interface.
- Local density fluctuations show large variances, exceeding ideal gas predictions.
- Water interfaces exhibit flickering, with slow transitions between wet and dry regions.
Conclusions:
- Capillary-wave fluctuations significantly broaden water interfaces around large nonpolar solutes.
- The interface behaves similarly to a free liquid-vapor interface in terms of broadening and tension.
- Dynamic fluctuations lead to slow, flickering transitions between wet and dry regions on the interface.
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