New paradigm for configurational entropy in glass-forming systems

Abstract

We show that on cooling towards glass transition configurational entropy exhibits more significant changes than predicted by classic relation. A new formula according to Kauzmann temperature TK is given: S=S0tn, where t=(T-TK)/T. The exponent n is hypothetically linked to dominated local symmetry. Such a behaviour is coupled to previtreous evolution of heat capacity Cp(T)=(nC/T)(1-TK/T)n-1 associated with finite temperature singularity. These lead to generalised VFT relation, for which the basic equation is retrieved. For many glass-formers, basic VFT equation may have only an effective meaning. A universal-like reliability of the Stickel operator analysis for detecting dynamic crossover phenomenon is also questioned. Notably, distortions-sensitive and derivative-based analysis focused on previtreous changes of configurational entropy and heat capacity for glycerol, ethanol and liquid crystal is applied.