Adam-Gibbs model in the density scaling regime and its implications for the configurational entropy scaling

Abstract

To solve a long-standing problem of condensed matter physics with determining a proper description of the thermodynamic evolution of the time scale of molecular dynamics near the glass transition, we have extended the well-known Adam-Gibbs model to describe the temperature-volume dependence of structural relaxation times, τα (T, V). We also employ the thermodynamic scaling idea reflected in the density scaling power law, τα = f(T-1 V-γ), recently acknowledged as a valid unifying concept in the glass transition physics, to differentiate between physically relevant and irrelevant attempts at formulating the temperature-volume representations of the Adam-Gibbs model. As a consequence, we determine a straightforward relation between the structural relaxation time τα and the configurational entropy S C, giving evidence that also SC (T, V) = g(T-1 V-γ) with the exponent γ that enables to scale τα (T, V). This important findings have meaningful implications for the connection between thermodynamics and molecular dynamics near the glass transition, because it implies that τα can be scaled with S C