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Self-Averaging Fluctuations in the Chaoticity of Simple Fluids
Moupriya Das1, Jason R Green1,2,3
1Department of Chemistry, University of Massachusetts Boston, Boston, Massachusetts 02125, USA.
Physical Review Letters
|September 27, 2017
Summary
Intermolecular forces in simple fluids influence dynamical fluctuations. Repulsive forces dominate over attractive ones, impacting how Lyapunov exponents approach the thermodynamic limit.
Area of Science:
- Thermodynamics
- Statistical Mechanics
- Fluid Dynamics
Background:
- Bulk properties of equilibrium liquids arise from intermolecular forces.
- Dynamical fluctuations offer insights into molecular interactions.
Purpose of the Study:
- Investigate the imprint of intermolecular forces on Lyapunov exponents in simple fluids.
- Analyze the self-averaging behavior of dynamical fluctuations and their relation to intermolecular force characteristics.
Main Methods:
- Simulation of simple fluids with varying intermolecular forces (repulsive and attractive).
- Calculation and analysis of Lyapunov exponents and their fluctuations.
- Examination of self-averaging properties and convergence to the thermodynamic limit.
Main Results:
- The first Lyapunov exponent exhibits weak self-averaging, dependent on intermolecular force length scales.
- Short-range repulsive forces play a dominant role compared to longer-range attractive forces.
- Fluctuations in Kolmogorov-Sinai entropy rate diverge, consistent with extensive quantities.
- Dynamical observable fluctuations follow fluctuation-dissipation-like relationships.
Conclusions:
- Intermolecular forces significantly shape the dynamics of simple fluids.
- The findings align with the van der Waals model of fluids.
- Lyapunov exponents provide a novel perspective for understanding liquid states.
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