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Updated: May 28, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Liquid water: from symmetry distortions to diffusive motion
1The Fritz Haber Research Center, Institute of Chemistry, The Hebrew University of Jerusalem, Israel. agmon@fh.huji.ac.il
Accounts of Chemical Research
|October 8, 2011
Summary
Water
Area of Science:
- Physical Chemistry
- Chemical Physics
- Molecular Dynamics
Background:
- Water's tetrahedral symmetry is often oversimplified, masking inherent molecular distortions crucial for its dynamics.
- An isolated water molecule exhibits an asymmetric charge distribution, featuring a "negativity track" that facilitates molecular motion.
- Hydrogen-bond (HB) dynamics in water show asymmetry between donor and acceptor roles, influencing liquid water's structure.
Purpose of the Study:
- To investigate the manifestations of water's structural distortions from isolated molecules to the liquid phase.
- To elucidate the role of asymmetric charge distribution in water's hydrogen-bond dynamics and self-diffusion.
- To model the key reactions governing hydrogen-bond switching and their impact on water's collective behavior.
Main Methods:
- Analysis of molecular dynamics simulations to observe hydrogen-bond distributions.
- Development of a simplified reaction model to explain hydrogen-bond dynamics.
- Comparison of water self-diffusion coefficients with Debye relaxation times.
Main Results:
- Liquid water displays asymmetry in hydrogen-bond acceptance versus donation, favoring trigonal coordination.
- A two-reaction model (HB dissociation and switching) quantitatively explains observed hydrogen-bond distributions.
- Water self-diffusion dynamics correlate with Debye relaxation, indicating coupled rotational and translational motion.
Conclusions:
- Water's plasticity and unique dynamics stem from its asymmetric charge distribution and the interplay between tetrahedral and trigonal coordination states.
- Hydrogen-bond switching is a key mechanism driving water's collective molecular motions.
- The study provides a quantitative model for hydrogen-bond dynamics and self-diffusion in water.
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