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Dynamics of simulated water under pressure
F W Starr1, F Sciortino, H E Stanley
1Center for Polymer Studies, Center for Computational Science, and Department of Physics, Boston University, Boston, Massachusetts 02215, USA. fstarr@nist.gov
Summary
Molecular dynamics simulations reveal water
Area of Science:
- Computational physics
- Physical chemistry
- Soft matter physics
Background:
- Water exhibits complex dynamic and structural properties under varying temperatures and pressures.
- Understanding these properties is crucial for various scientific disciplines.
- Mode-Coupling Theory (MCT) provides a framework for describing the dynamics of supercooled liquids.
Purpose of the Study:
- To investigate the dynamic properties of water using molecular dynamics simulations.
- To compare simulation results with experimental data and theoretical predictions.
- To explore the validity of Mode-Coupling Theory (MCT) in a broad range of conditions.
Main Methods:
- Extended simple-point-charge (SPC/E) model for water.
- Molecular dynamics simulations.
- Varying temperatures (190 K to 350 K) and pressures (-300 MPa to 2.5 GPa).
Main Results:
- Simulations reproduce the experimentally observed diffusivity maximum as a function of pressure.
- Results align with MCT predictions for weakly supercooled liquids.
- Evidence of a crossover from power-law to Arrhenius behavior in diffusivity at low temperatures.
Conclusions:
- Simulation findings support the hypothesis that dynamic property divergences are independent of thermodynamic singularities.
- MCT predictions are confirmed over an extended range of the von Schweidler exponent.
- Structural changes in water correlate with dynamic properties, providing insights into liquid behavior.