Comment on “Correlation between configurational entropy and structural relaxation time in glass-forming liquids”

Abstract

An empirical formalism proposed by Prevosto et al. for distinguishing between the effects of temperature and pressure changes on the configurational entropy of supercooled liquids (to extend the Adam-Gibbs equation to high pressures) defines this quantity by a line integral in the $T,P$ plane. They, however, appear to have overlooked a mathematical requirement that a function of state must meet: in brief, its two mixed second derivatives must be equal, independent of the order of differentiation. If this requirement is introduced, either a physically implausible constraint is imposed on their configurational entropy, or else it is not a function of state.