Dynamic phase coexistence in glass–forming liquids

Pastore, Raffaele; Coniglio, Antonio; Ciamarra, Massimo Pica

doi:10.1038/srep11770

Cited by 40 publications

(55 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The SEB in the KA model is well documented [12,14,[38][39][40][41][42]. In the KA model, for k = k * (∼ 7.25) (first peak of the static structure factor S(k)), the SE relation breaks down close to the onset temperature of slow dynamics.…”

mentioning

confidence: 95%

“…DH simply means that there are populations of slow and fast particles which form transient clusters, making the dynamics spatially heterogeneous. The existence of DH leads to the expectation of a distribution of diffusion coefficients and relaxation times [12,14] corresponding to populations of different mobility. The observed D is dominated by the fast population, while the observed τ (or η) is governed mainly by the slow population, leading to the decoupling and the SEB.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Length-Scale Dependence of the Stokes-Einstein and Adam-Gibbs Relations in Model Glass Formers

2017

View full text Add to dashboard Cite

The Adam-Gibbs (AG) relation connects the dynamics of a glass-forming liquid to its the thermodynamics via. the configurational entropy, and is of fundamental importance in descriptions of glassy behaviour. The breakdown of the Stokes-Einstein (SEB) relation between the diffusion coefficient and the viscosity (or structural relaxation times) in glass formers raises the question as to which dynamical quantity the AG relation describes. By performing molecular dynamics simulations, we show that the AG relation is valid over the widest temperature range for the diffusion coefficient and not for the viscosity or relaxation times. Studying relaxation times defined at a given wavelength, we find that SEB and the deviation from the AG relation occur below a temperature at which the correlation length of dynamical heterogeneity equals the wavelength probed.It is now clear from extensive research over the last two decades that, as a liquid is gradually (super)cooled, its dynamics becomes spatially heterogeneous ("dynamical heterogeneity") [1][2][3] and the collective nature of the underlying relaxation processes can be quantified by various growing correlation length scales [4, 5]. Dynamics can be described by different measures -the translational diffusion coefficient (D), the shear viscosity (η) or the α-relaxation time (τ α ). At high temperatures, where particle motions are diffusive, all these time scales are mutually coupled. D and η are related via the Stokes-Einstein (SE) relation [6, 7] : D = mk B cπ T Rη , (m, R are respectively mass and radius of a diffusing particle, T is the temperature of the liquid and the constant c depends on stick or slip boundary condition). At high temperatures, owing to exponential decay of self-intermediate scattering function F s (k, t) = exp(−Dk 2 t) at all probe wave vectors k, D also gets coupled to the relaxation time τ (k) measured from F s (k, t) : Dk 2 τ (k) = constant. Further, τ α is often used as a proxy for η (or η/T ) in the SE relation to save computational cost. At low temperatures in dense, viscous liquids, D becomes much bigger than the value estimated from τ α (η) using the SE relation. This phenomenon is known as the breakdown of the SE relation (SEB) [2,[8][9][10][11][12][13] [1, 2, 7, 8] interprets the SEB as a consequence of the dynamical heterogeneity (DH) developing in the liquid upon cooling. DH simply means that there are populations of slow and fast particles which form transient clusters, making the dynamics spatially heterogeneous. The existence of DH leads to the expectation of a distribution of diffusion coefficients and relaxation times [12,14] corresponding to populations of different mobility. The observed D is dominated by the fast population, while the observed τ (or η) is governed mainly by the slow population, leading to the decoupling and the SEB. The observed decoupling (SEB) is an average effect in such a picture, which however, does not clarify the role played by a heterogeneity length scale.The breakdown of the SE relation poses a puzzle...

show abstract

mentioning

confidence: 95%

mentioning

confidence: 99%

Length-Scale Dependence of the Stokes-Einstein and Adam-Gibbs Relations in Model Glass Formers

2017

View full text Add to dashboard Cite

show abstract

“…Pastore et al have recently developed a cage-jump model to predict the long-time diffusivity from the shorttime cage dynamics in supercooled liquids. [26][27][28][29][30][31] In the study, a trajectory of a single particle is segmented into a) Electronic mail: kk@cheng.es.osaka-u.ac.jp b) Electronic mail: nobuyuki@cheng.es.osaka-u.ac.jp caged and jumping states. The segmentation criterion was given by the MSD plateau value.…”

Section: Introductionmentioning

confidence: 99%

Diffusion dynamics of supercooled water modeled with the cage-jump motion and hydrogen-bond rearrangement

Kikutsuji

Kim

Matubayasi

2019

The Journal of Chemical Physics

View full text Add to dashboard Cite

The slow dynamics of glass-forming liquids is generally ascribed to the cage-jump motion. In the cage-jump picture, a molecule remains in a cage formed by neighboring molecules, and after a sufficiently long time, it jumps to escape from the original position by cage-breaking. The clarification of the cage-jump motion is therefore linked to unraveling the fundamental element of the slow dynamics. Here, we develop a cagejump model for the dynamics of supercooled water. The caged and jumping states of a water molecule are introduced with respect to the hydrogen-bond (H-bond) rearrangement process, and describe the motion in supercooled states. It is then demonstrated from the molecular dynamics simulation of the TIP4P/2005 model that the characteristic length and time scales of cage-jump motions provide a good description of the selfdiffusion constant that is determined in turn from the long-time behavior of the mean square displacement. Our cage-jump model thus enables to connect between H-bond dynamics and molecular diffusivity. arXiv:1903.06060v2 [cond-mat.soft]

show abstract

“…Here we show that the jumps we have identified are irreversible, and we give evidence suggesting that these can be considered as 'elementary' irreversible events, i.e that they are the smallest irreversible single-particle move, at least in the range of parameters we have investigated. Investigating both the model considered here 32 , as well as the 3d Kob-Andersen Lennard-Jones (3d KA LJ) binary mixture 34 and experimental colloidal glass 35 , we have previously shown that the protocol defined in Sec. 2 leads to the identification of irreversible events.…”

Section: Jumps As Irreversible Elementary Processesmentioning

confidence: 99%

Spatial correlations of elementary relaxation events in glass-forming liquids

2015

Self Cite

View full text Add to dashboard Cite

The dynamical facilitation scenario, by which localized relaxation events promote nearby relaxation events in an avalanching process, has been suggested as the key mechanism connecting the microscopic and the macroscopic dynamics of structural glasses. Here we investigate the statistical features of this process via the numerical simulation of a model structural glass. First we show that the relaxation dynamics of the system occurs through particle jumps that are irreversible, and that cannot be decomposed in smaller irreversible events. Then we show that each jump does actually trigger an avalanche. The characteristic of this avalanche change on cooling, suggesting that the relaxation dynamics crossovers from a noise dominated regime where jumps do not trigger other relaxation events, to a regime dominated by the facilitation process, where a jump trigger more relaxation events.

show abstract

Dynamic phase coexistence in glass–forming liquids

Cited by 40 publications

References 46 publications

Length-Scale Dependence of the Stokes-Einstein and Adam-Gibbs Relations in Model Glass Formers

Length-Scale Dependence of the Stokes-Einstein and Adam-Gibbs Relations in Model Glass Formers

Diffusion dynamics of supercooled water modeled with the cage-jump motion and hydrogen-bond rearrangement

Spatial correlations of elementary relaxation events in glass-forming liquids

Contact Info

Product

Resources

About