Density Scaling and Dynamic Correlations in Viscous Liquids

Fragiadakis, D.; Casalini, R.; Roland, C. M.

doi:10.1021/jp907553b

Cited by 35 publications

(58 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It also shows that at fixed ‫ء‬ , the dynamic correlations are invariant to either T or , as expected from the density scaling of both the average dynamics and the dynamic correlations for the same value of ␥. Recent experiments 19 have shown that a similar result holds for the temperature derivatives of the two point dynamic correlation function T ͑t͒, which provides a lower bound to 4 ͑t͒. 16,17 This correspondence supports the validity of the experimentally accessible T ͑t͒ as an approximation to 4 ͑t͒.…”

Section: ͑4͒supporting

confidence: 70%

“…16 Recent numerical and simulation works have shown that the dynamic correlation volume grows upon cooling. [17][18][19] However, very little is known about the combined temperature and density dependences of 4 ͑t͒. In particular, unexplored is the possibility of a description of the and T dependences of 4 ͑t͒ in terms of the scaling property established for the structural relaxation time [20][21][22] …”

Section: Density Scaling In Viscous Liquids: From Relaxation Times Tomentioning

confidence: 99%

See 1 more Smart Citation

Density scaling in viscous liquids: From relaxation times to four-point susceptibilities

Coslovich

Roland

2009

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

We present numerical calculations of a four-point dynamic susceptibility, χ4(t), for the Kob-Andersen Lennard-Jones mixture as a function of temperature T and density ρ. Over a relevant range of T and ρ, the full t-dependence of χ4(t) and thus the maximum in χ4(t), which is proportional to the dynamic correlation volume, are invariant for state points for which the scaling variable ρ γ /T is constant. The value of the material constant γ is the same as that which superposes the relaxation time, τ , of the system versus ρ γ /T . Thus, the dynamic correlation volume is a unique function of τ for any thermodynamic condition in the regime where density scaling holds. Finally, we examine the conditions under which the density scaling properties are related to the existence of strong correlations between pressure and energy fluctuations.

show abstract

Section: ͑4͒supporting

confidence: 70%

Section: Density Scaling In Viscous Liquids: From Relaxation Times Tomentioning

confidence: 99%

Density scaling in viscous liquids: From relaxation times to four-point susceptibilities

Coslovich

Roland

2009

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…lines of equal relaxation time). Contrary to previous reports [16,17] and to theoretical predictions [26,27], the extent of the spatial correlations in the dynamics is therefore not uniquely determined by the relaxation time. …”

Section: ∂F(t)contrasting

confidence: 94%

“…However, except for partial results at atmospheric pressure [11], this latter procedure was never attempted. Previous pressure studies along several isobars considered the crudest bound on χ 4 (t) only [16,17].…”

Section: ∂F(t)mentioning

confidence: 99%

Effect of pressure on the number of dynamically correlated molecules when approaching the glass transition

Alba‐Simionesco¹,

Dalle-Ferrier²,

Tarjus³

2013

AIP Conference Proceedings

View full text Add to dashboard Cite

We characterize the heterogeneous character of the dynamics of liquids approaching the glass transition through an experimental determination of the number of dynamically correlated molecules N corr as obtained from dynamical susceptibilities. To do so, we have obtained a new set of dielectric spectroscopy data for liquid dibutyl-phtalate on a fine and extended temperature and pressure grid, and we have used it in conjunction with high-pressure data from the literature. We have been able to evaluate the contributions to N corr that are due to fluctuations associated with density and with temperature separately, thereby improving the estimate of N corr . We find that N corr increases along the glass transition line, and more generally along any isochronic line, as pressure increases (up to 1 GPa), a result which is at odds with recent reports and theoretical predictions.

show abstract

“…A recently developed four-point correlation method 14 allows to estimate the size of this region from the temperature dependence of, say, the dielectric susceptibility [47][48][49] . The average number of inherent states in such a cooperatively rearranging region can be calculated from the asymmetry model 23 , because the f N for just two inherent states with asymmetry 4k B T in the core is 0.012.…”

Section: Discussionmentioning

confidence: 99%

On the mechanism of the highly viscous flow

Buchenau

2011

The Journal of Chemical Physics

View full text Add to dashboard Cite

The asymmetry model for the highly viscous flow postulates thermally activated jumps from a practically undistorted ground state to strongly distorted, but stable structures, with a pronounced Eshelby backstress from the distorted surroundings. The viscosity is ascribed to those stable distorted structures which do not jump back, but relax by the relaxation of the surrounding viscoelastic matrix. It is shown that this mechanism implies a description in terms of the shear compliance, with a viscosity which can be calculated from the cutoff of the retardation spectrum. Consistency requires that this cutoff lies close to the Maxwell time. The improved asymmetry model compares well with experiment.

show abstract

Density Scaling and Dynamic Correlations in Viscous Liquids

Abstract: We use a recently proposed method [Berthier L.; Biroli G.; Bouchaud J.P.;

Cited by 35 publications

References 55 publications

Density scaling in viscous liquids: From relaxation times to four-point susceptibilities

Density scaling in viscous liquids: From relaxation times to four-point susceptibilities

Effect of pressure on the number of dynamically correlated molecules when approaching the glass transition

On the mechanism of the highly viscous flow

Contact Info

Product

Resources

About