A test of non-equilibrium thermodynamics in glassy systems: the soft-sphere case

TL;DR

This paper tests non-equilibrium thermodynamics in glassy systems using soft-sphere potentials, deriving an exact expression for pressure in frozen liquids and validating the extension of free energy concepts to out-of-equilibrium states.

Contribution

It provides an exact expression for the pressure of glassy states in soft-sphere systems and validates the non-equilibrium free energy framework for describing such states.

Findings

Exact pressure expression for frozen liquids derived

Non-equilibrium free energy accurately describes glass states

Supports extension of thermodynamic concepts to out-of-equilibrium systems

Abstract

The scaling properties of the soft-sphere potential allow the derivation of an exact expression for the pressure of a frozen liquid, i.e., the pressure corresponding to configurations which are local minima in its multidimensional potential energy landscape. The existence of such a relation offers the unique possibility for testing the recently proposed extension of the liquid free energy to glassy out-of-equilibrium conditions and the associated expression for the temperature of the configurational degrees of freedom. We demonstrate that the non-equilibrium free energy provides an exact description of the soft-sphere pressure in glass states.