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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Hydrogen bonding definitions and dynamics in liquid water
R Kumar1, J R Schmidt, J L Skinner
1Theoretical Chemistry Institute, and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
The Journal of Chemical Physics
|June 8, 2007
Summary
Researchers developed new methods to define hydrogen bonding in water, improving accuracy. This study estimates 3.2-3.4 hydrogen bonds per molecule and reveals local structural relaxation dynamics.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Materials Science
Background:
- Hydrogen bonding in water is crucial for its properties.
- Existing geometric definitions of hydrogen bonds are often arbitrary.
- Interpreting experimental data like X-ray diffraction relies on accurate hydrogen bond definitions.
Purpose of the Study:
- To develop a systematic and more accurate definition of hydrogen bonding in liquid water.
- To establish a procedure for defining hydrogen bond cutoffs using distance and angular coordinates.
- To investigate the dynamics of hydrogen bond fluctuations and their relation to structural relaxation.
Main Methods:
- Utilized two-dimensional potentials of mean force to define hydrogen bond cutoffs.
- Developed an electronic structure-based definition of hydrogen bonding.
- Analyzed experimental data from X-ray and neutron diffraction, and spectroscopy.
- Examined dynamics of local hydrogen-bond number fluctuations using simulations.
Main Results:
- A systematic procedure for defining hydrogen bond cutoffs was established.
- An electronic structure-based definition showed compatibility with geometric definitions.
- Estimated 3.2-3.4 hydrogen bonds per molecule in SPC/E water.
- Found a long-time decay constant for local structural relaxation between 0.8-0.9 ps.
Conclusions:
- The developed definitions provide a more robust framework for studying water's hydrogen bond network.
- The findings offer insights into the dynamics of local structure and relaxation in liquid water.
- This work bridges experimental interpretation with theoretical definitions of hydrogen bonding.
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