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Published on: December 4, 2017
Hidden scale invariance in molecular van der Waals liquids: a simulation study
Thomas B Schrøder1, Ulf R Pedersen, Nicholas P Bailey
1DNRF Centre Glass and Time, IMFUFA, Department of Sciences, Roskilde University, Post Box 260, DK-4000 Roskilde, Denmark.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 13, 2009
Summary
Viscous molecular liquids exhibit hidden approximate scale invariance, with potential energy fluctuations and radial distribution functions accurately described by inverse power-law (IPL) potentials. This IPL scaling extends to dynamics but not the equation of state for van der Waals liquids.
Area of Science:
- Condensed matter physics
- Computational chemistry
- Statistical mechanics
Background:
- Understanding the behavior of viscous molecular liquids is crucial for materials science and chemical engineering.
- Previous studies have explored liquid properties using molecular dynamics simulations, but scale invariance in these systems remains an area of investigation.
Purpose of the Study:
- To investigate the presence and extent of approximate scale invariance in viscous molecular liquids.
- To determine if inverse power-law (IPL) potentials can accurately describe equilibrium and dynamic properties.
- To assess the generalizability of observed scaling behaviors across different types of liquids.
Main Methods:
- Utilizing molecular dynamics simulations for two distinct viscous molecular models: the Lewis-Wahnström model of orthoterphenyl and an asymmetric dumbbell model.
- Analyzing equilibrium potential energy fluctuations and radial distribution functions.
- Examining the dynamic properties and the equation of state of the simulated liquids.
Main Results:
- Demonstrated a "hidden" approximate scale invariance in the studied viscous liquids.
- Showed that equilibrium potential energy fluctuations and radial distribution functions are accurately described by inverse power-law (IPL) potentials.
- Confirmed that IPL scaling applies to the dynamics, with a scaling exponent predicted by equilibrium fluctuations, but not to the equation of state.
Conclusions:
- The findings suggest that approximate scale invariance, characterized by IPL potentials, is a general feature of van der Waals liquids.
- The observed scaling properties are not applicable to hydrogen-bonded liquids.
- This research provides new insights into the fundamental physical principles governing the behavior of complex molecular liquids.
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