Decrease in the configurational and vibrational entropies on supercooling a liquid and their relations with the excess entropy

Molecular Mobility, Thermodynamics and Stability of Griseofulvin’s Ultraviscous and Glassy States from Dynamic Heat Capacity

“…In contrast, C p ¶ and C p,app of the glassy state are the sum of contributions mainly from vibrations, with two small contributions from molecular kinetics, one from localized motions of the JG relaxation (26)(27)(28)(29)(30)(31) and the second from the kinetically unfrozen faster modes in the distribution of the a-relaxation process (28)(29)(30)(31). These contributions decrease during storage as the glass structure relaxes spontaneously to a state of lower fictive temperature T f (the temperature at which the glass and the liquid have the same properties) volume, enthalpy and entropy (32)(33)(34)(35)(36) because the vibrational frequency increases, the vibrational amplitude, the a-relaxation contribution and the JG relaxation contribution decrease-the decrease in the last one due to decrease in the number of molecules involved in localized motions (34)(35)(36)(37)(38)(39)(40)(41)(42).…”

“…The dynamic heat capacity at a temperature T measured for a fixed w mod is given by (23,(29)(30)(31)43),…”

Relation between configurational entropy and relaxation dynamics of glass-forming systems under volume and temperature reduction

“…This approximation gave rise to several criticisms [16]. The main one is that the vibrational properties of a crystal are different from that of the supercooled liquid at the same T-P conditions and so a vibrational excess term is considerably contributing to S exc [16].…”

“…This approximation gave rise to several criticisms [16]. The main one is that the vibrational properties of a crystal are different from that of the supercooled liquid at the same T-P conditions and so a vibrational excess term is considerably contributing to S exc [16]. As in supercooled liquids a relation log[τ(T,P)]∝[TS exc (T,P)] -1 is usually fulfilled [12,13,14,15], a hypotesis about the proportionality S exc ∝S C was proposed, yielding again the relation of Eq.…”

“…Notwithstanding the above mentioned results appear as convincing tests of the AG model, the debate is still open about several issues: (a) the right way of calculating the configurational entropy in an experiment [16,19,20,21]; (b) the physical meaning of the size of a CRR [21,22,23,24]; (c) the amount of configurational part of S exc [7,17,16,25,21,26,27,28,18]; (d) the independence from pressure and temperature of the coefficient C AG in Eq.…”