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Relation between rotational and translational dynamic heterogeneities in water
Marco G Mazza1, Nicolas Giovambattista, Francis W Starr
1Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215, USA.
Physical Review Letters
|February 21, 2006
Summary
Molecular dynamics simulations reveal spatial heterogeneity in water's rotational dynamics. Clusters of faster-rotating molecules correlate with translational heterogeneity, becoming more prevalent at lower temperatures.
Area of Science:
- Computational chemistry
- Physical chemistry
- Condensed matter physics
Background:
- Understanding water's complex dynamics is crucial for various scientific fields.
- Previous studies suggest non-uniform molecular motion in supercooled liquids.
Purpose of the Study:
- To investigate the rotational dynamics of the extended simple point charge (SPC/E) water model.
- To explore the spatial heterogeneity of rotational motion near the mode coupling temperature.
Main Methods:
- Performing molecular dynamics (MD) simulations of the SPC/E water model.
- Analyzing rotational dynamics at temperatures down to 200 K.
Main Results:
- Observed spatial heterogeneity in rotational dynamics, with clusters of faster-rotating molecules.
- Found strong correlation between rotational and translational heterogeneity positions.
- Noted an increase in the fraction of molecules exhibiting both heterogeneities as temperature decreased.
Conclusions:
- Rotational dynamics in SPC/E water exhibit significant spatial heterogeneity.
- Translational and rotational heterogeneities are linked to the same underlying physical phenomena.
- The degree of heterogeneity increases with decreasing temperature, approaching the mode coupling transition.