The new insight into dynamic crossover in glass forming liquids from the apparent enthalpy analysis

Abstract

Dynamics of glass-forming liquids. V. On the link between molecular dynamics and configurational entropy The Journal of Chemical Physics 108, 9016 (1998) (2011)]. We present a qualitatively new way to identify the dynamic crossover based on the apparent enthalpy space (H a = d ln τ /d(1/T )) analysis via a new plot ln H a vs. 1/T supported by the Savitzky-Golay filtering procedure for getting an insight into the noise-distorted high order derivatives. It is shown that depending on the ratio between the "virtual" fragility in the high temperature dynamic domain (m high ) and the "real" fragility at T g (the low temperature dynamic domain, m = m low ) glass formers can be splitted into two groups related to f < 1 and f > 1, (f = m high /m low ). The link of this phenomenon to the ratio between the apparent enthalpy and activation energy as well as the behavior of the configurational entropy is indicated.

Mean-field dynamic criticality and geometric transition in the Gaussian core model

“…Experimental data at ambient [12,13] and high pressure [14], as well as recent simulation results [15] hint at a dynamic crossover at a temperature higher than T g . Around the crossover, however, other physical mechanisms, such as dynamic facilitation [16] and/or local structure formation [17], may play an important role and compete with the mean-field scenario.…”

The Boson peak in confined water: An experimental investigation of the liquid-liquid phase transition hypothesis

“…Besides the anomalous increase of more than a factor of 10 13 in the transport parameters (viscosity, self-diffusion, and relaxation times) that results in the continuous transition from a fluid to a glass, it is commonly accepted that two characteristic features dominate the behavior of glassy liquids as they evolve toward the glass state: i) the appearance of dynamic heterogeneities [2] and ii) the complicated energy landscape [3][4][5][6][7]. Just by observing the transport properties of a typical glass-forming supercooled liquid, it can be classified as being a strong (where the activation energies are well defined) or a fragile liquid [8,9]; hence, a nearly Arrhenius temperature dependence is characteristic of a strong liquid, whereas a fragile liquid shows a quite non-Arrhenius behavior.…”

“…Its appearance indicates that the sys- tem is approaching the dynamic arrest [6,7,9,21,22,37]; many special processes occur at the dynamic arrest (at FSDC) (see, e.g., Ref. [9]), including the violation of the Stokes-Einstein law [2], orientational-translational decoupling [4], splitting of the relaxation into primary (α) and secondary relaxation times (β), onset of dynamic heterogeneities, and onset of the Boson peak (BP) [2,[24][25][26].…”

The fragile-to-strong dynamical crossover and the system viscoelasticity in attractive glass forming colloids

“…On these bases, various recent studies [6,22,24] propose to consider at least two dynamic regimes in order to study the supercooled liquid dynamics in a broader range of temperature. In fact, an intriguing and important phenomenon manifests at a temperature between T g and T M inside the supercooled phase [25]: the so called fragile-to-strong dynamic crossover (FSDC) occurring at T B (T g < T B < T M ).…”