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Conservation of the Stokes-Einstein relation in supercooled water
Gan Ren1, Yanting Wang2,3
1School of Science, Civil Aviation Flight University of China, Guanghan 628307, China.
Physical Chemistry Chemical Physics : PCCP
|November 1, 2021
Summary
The Stokes-Einstein relation holds true for supercooled water, contrary to common belief. Molecular dynamics simulations reveal that previous studies incorrectly applied variants of the relation, leading to false conclusions about its breakdown.
Area of Science:
- Physical Chemistry
- Water Science
- Statistical Mechanics
Background:
- The Stokes-Einstein relation is a fundamental concept in physical chemistry describing particle diffusion.
- Previous studies suggested the Stokes-Einstein relation breaks down in supercooled water.
- This apparent breakdown contradicts the local equilibrium state of supercooled water.
Purpose of the Study:
- To re-evaluate the validity of the original Stokes-Einstein relation in supercooled water.
- To investigate the reasons for the perceived inconsistency with existing experimental data.
- To clarify the behavior of the Stokes-Einstein relation under supercooling conditions.
Main Methods:
- Molecular dynamics simulations were employed to model water behavior.
- The original form of the Stokes-Einstein relation was analyzed.
- Temperature-dependent effective hydrodynamic radius and shear viscosity were calculated.
Main Results:
- The Stokes-Einstein relation is conserved in supercooled water.
- Inconsistencies arise from approximate variants and temperature-dependent effective radius.
- The effective hydrodynamic radius decreases with decreasing temperature, not constant.
Conclusions:
- The Stokes-Einstein relation is valid for supercooled water.
- Previous conclusions of breakdown were based on flawed application of relation variants.
- Accurate application of the Stokes-Einstein relation requires accounting for temperature-dependent parameters.
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