Nonequilibrium thermodynamics of the Kovacs effect†
Abstract
We present a thermodynamic theory of the Kovacs effect based on the idea that the configurational degrees of freedom of a glass-forming material are driven out of equilibrium with the heat bath by irreversible thermal contraction and expansion. We assume that the slowly varying configurational subsystem, i.e. the part of the system that is described by inherent structures, is characterized by an effective temperature, and contains a volume-related internal variable. We examine mechanisms by which irreversible dynamics of the fast, kinetic-vibrational degrees of freedom can cause the entropy and the effective temperature of the configurational subsystem to increase during sufficiently rapid changes in the bath temperature. We then use this theory to interpret the numerical simulations by Mossa and Sciortino (
- This article is part of the themed collection: Granular and jammed materials