Evidence for structural crossover in the supercritical state

Abstract

The state of matter above the critical point is terra incognita, and is loosely discussed as a physically homogeneous flowing state where no differences can be made between a liquid and a gas and where properties undergo no marked or distinct changes with pressure and temperature. In particular, the structure of supercritical state is currently viewed to be the same everywhere on the phase diagram, and to change only gradually and in a featureless way while moving along any temperature and pressure path above the critical point. Here, we demonstrate that this is not the case, but that there is a well-defined structural crossover instead. Evidenced by the qualitative changes of distribution functions of interatomic distances and angles, the crossover demarcates liquid-like and gas-like configurations and the presence of medium-range structural correlations. Importantly, the discovered structural crossover is closely related to both dynamic and thermodynamic crossovers operating in the supercritical state, providing new unexpected fundamental interlinks between the supercritical structure, dynamics and thermodynamics.

5 pages, 4 figures

References in corpus (6)

• Irreversible reorganization in a supercooled liquid originates from localised soft modes
• "Liquid-gas" transition in the supercritical region: Fundamental changes in the particle dynamics
• Thermodynamic behavior of supercritical matter
• Two stage order-disorder transformation in simple monatomic supercritical fluid: superstable tetrahedral local order
• Symmetry breaking gives rise to energy spectra of three states of matter
• Helium at elevated pressures: Quantum liquid with non-static shear rigidity

Cited by in corpus (17)

• The Frenkel Line: a direct experimental evidence for the new thermodynamic boundary
• Experimental evidence of the Frenkel line in supercritical neon
• Unified phonon-based approach to the thermodynamics of solid, liquid and gas states
• Revealing the Mechanism of the Viscous-to-Elastic Crossover in Liquids
• The "True" Widom Line for a Square-Well System
• Persistent local order heterogeneity in the supercritical carbon dioxide
• Thermally triggered phononic gaps in liquids at THz scale
• Structural behavior of supercritical fluids under confinement
• Direct links between dynamical, thermodynamic and structural properties of liquids: modelling results
• Topological Characterization of Rigid-Nonrigid Transition across the Frenkel Line
• Dynamic transition of supercritical hydrogen in gas giants: defining the boundary between interior and atmosphere
• Experimental observation of gapped shear waves and liquid-like to gas-like dynamical crossover in active granular matter
• Mesoscopic Collective Dynamics in Liquids and the Dual Model
• On a conjecture concerning the Fisher--Widom line and the line of vanishing excess isothermal compressibility in simple fluids
• The Viscosity of Liquids in the Dual Model
• Revisiting the question of what instantaneous normal modes tell us about liquid dynamics
• Theory of dipolaron solutions