Universal interrelation between dynamics and thermodynamics of fluids: dynamically-driven "c"-transition

TL;DR

This study uncovers a universal, path-independent transition between liquidlike and gaslike states in supercritical fluids, characterized by a specific heat and dynamical parameters, suggesting a potential new phase transition or sharp crossover.

Contribution

It introduces the concept of a 'c'-transition, revealing a universal interrelation between dynamics and thermodynamics in supercritical fluids across various conditions.

Findings

Data collapse of specific heat versus dynamical parameters

Path-independent transition observed in supercritical phase diagram

Existence of a fixed inversion point indicating a possible new phase transition

Abstract

Our first very wide survey of the supercritical phase diagram and its key properties reveals a universal interrelation between dynamics and thermodynamics and an unambiguous transition between liquidlike and gaslike states. This is seen in the master plot showing a collapse of the data representing the dependence of specific heat on key dynamical parameters in the system for many different paths on the phase diagram. As a result, the observed transition is path-independent. We call it a "c"-transition due to the "c"-shaped curve parameterizing the dependence of the specific heat on key dynamical parameters. The "c"-transition has a fixed inversion point and provides a new structure to the phase diagram, operating deep in the supercritical state (up to at least 2000 times the critical pressure and 50 times the critical temperature). The data collapse and path independence as well as the existence of a special inversion point on the phase diagram are indicative of either of a sharp crossover or a new phase transition in the deeply supercritical state.