Crossover of dynamical instability and chaos in the supercritical state

Abstract

We calculate the maximal Lyapunov exponent for a bulk system of 256 Lennard-Jones particles in constant energy molecular dynamics simulations deep into the supercritical state. We find that the maximal Lyapunov exponent undergoes a crossover, and that this crossover coincides with the dynamical crossover at the Frenkel line from liquid physics. We explain this crossover in terms of two different contributions to dynamical instability: diffusion in the liquid-like state below the Frenkel line, and collisions in the gas-like state above. These results provide insight into the phase space dynamics far from the melting line and densities where rare-gas approximation are inapplicable.

arXiv comment8 pages, 6 figures

References in corpus (19)

• Stochastic thermodynamics, fluctuation theorems, and molecular machines
• Relation Between the Widom line and the Strong-Fragile Dynamic Crossover in Systems with a Liquid-Liquid Phase Transition
• Two liquid states of matter: A new dynamic line on a phase diagram
• Collective modes and thermodynamics of the liquid state
• Elementary excitations and crossover phenomenon in liquids
• The phonon theory of liquid thermodynamics
• "Liquid-gas" transition in the supercritical region: Fundamental changes in the particle dynamics
• Chaotic Scattering Theory of Transport and Reaction-Rate Coefficients
• Emergence and evolution of $k$-gap in spectra of liquid and supercritical states
• Experimental evidence of the Frenkel line in supercritical neon
• Crossover between liquid-like and gas-like behaviour in CH4 at 400 K
• Lyapunov exponents as a dynamical indicator of a phase transition
• Curvature fluctuations and Lyapunov exponent at Melting
• Direct links between dynamical, thermodynamic and structural properties of liquids: modelling results
• Lyapunov Exponent and the Solid-Fluid Phase Transition
• Topological Characterization of Rigid-Nonrigid Transition across the Frenkel Line
• Experimental and modelling evidence for structural crossover in supercritical CO${}_2$
• Pronounced structural crossover in supercritical water
• Thermodynamic heterogeneity and crossover in the supercritical state of matter