From cage-jump motion to macroscopic diffusion in supercooled liquids

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

doi:10.1039/c4sm00739e

Cited by 56 publications

(92 citation statements)

References 47 publications

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“…A similar result was also reported in Ref. 26. It should be noted that ρ J is obtained by first analyzing each single-molecule trajectory and then taking an average over all the singlemolecule trajectories, while τ J and τ C are computed without distinguishing the trajectories of distinct water molecules.…”

Section: Resultssupporting

confidence: 77%

“…As discussed in Ref. 26, these features of the JMSD and D J indicate that the diffusion process of a single molecule can be described by the random walk with independent jumps, which is characterized by r 2 J . Furthermore, the decrease in D J with the temperature reduction is attributed to the corresponding decrease in the jumping length scale r 2 J .…”

Section: Resultsmentioning

confidence: 66%

“…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%

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

Kikutsuji

Kim

Matubayasi

2019

The Journal of Chemical Physics

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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]

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

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

Kikutsuji

Kim

Matubayasi

2019

The Journal of Chemical Physics

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“…We segment the trajectory of each particle in a series of cages interrupted by jumps using the algorithm of Ref. 32 , following earlier approaches 11 . Briefly, we consider that, on a timescale δ of few particle collisions, the fluctuation S 2 (t) of a caged particle position is of the order of the Debye-Waller factor (DWF) u 2 .…”

Section: Methodsmentioning

confidence: 99%

Spatial correlations of elementary relaxation events in glass-forming liquids

2015

Self Cite

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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.

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“…In the literature, DH is considered to be one of the fingerprints of vitrification, and its cause is attributed to consecutive intermittent jump motions of particles escaping out of cages [45][46][47][48][49]. To begin with, the system-size dependence of the self-part of the intermediate scattering function…”

mentioning

confidence: 99%

Unveiling Dimensionality Dependence of Glassy Dynamics: 2D Infinite Fluctuation Eclipses Inherent Structural Relaxation

et al. 2016

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By using large-scale molecular dynamics simulations, the dynamics of two-dimensional (2D) supercooled liquids turns out to be dependent on the system size, while the size dependence is not pronounced in three dimensional (3D) systems. It is demonstrated that the strong system-size effect in 2D amorphous systems originates from the enhanced fluctuations at long wavelengths, which are similar to those of 2D crystal phonons. This observation is further supported by the frequency dependence of the vibrational density of states, consisting of the Debye approximation in the low-wavenumber-limit. However, the system-size effect in the intermediate scattering function becomes negligible when the length scale is larger than the vibrational amplitude. This suggests that the finite-size effect in a 2D system is transient and also that the structural relaxation itself is not fundamentally different from that in a 3D system. In fact, the dynamic correlation lengths estimated from the bond-breakage function, which do not suffer from those enhanced fluctuations, are not size dependent in either 2D or 3D systems. PACS numbers: 62.60.+v, 61.20.Lc, Dimensionality plays a key role in the physics of solids and liquids -from high to low dimensions -and fluctuation shows up differently, as typically observed in phase transitions [1,2]. Indeed, two-dimensional (2D) systems often exhibit enhanced fluctuations, leading to various anomalies that are not experienced in three-dimensional (3D) systems. The melting of a 2D solid is a marked example [3][4][5][6][7][8][9], where the long-wavelength structural correlation is induced by thermal fluctuations sthat span an infinite length. For the glass transition from supercooled liquids to amorphous solids, the dimensionality dependence of the fluctuation has become an issue only recently. Gigantic fluctuation in 2D supercooled liquids has been observed that is far stronger than that in their 3D counterparts [10][11][12]. The aim of this Letter is to elucidate the similarity of this fluctuation to that in crystals [13], and also to investigate the heterogeneous dynamics in both 2D and 3D systems.For a crystalline solid of monodisperse particle assemblies, the mean-squared thermal displacement (MSTD) is given by using the vibrational density of state (VDOS) g(ω) as a function of angular frequency ω aswhere m the particle mass, d the spatial dimension, and (k B T ) −1 the inverse temperature. Under the Debye approximation for the VDOS of acoustic plane waves, g(ω) becomes proportional to ω d−1 [14]. It leads to divergence of the integral in 2D systems owing to the low-frequency acoustic waves, while it converges in 3D systems. As a result, the long-range translation order is prohibited in 2D systems [15,16]. Integration of Eq. (1) over ω ≥ 2πc/L provides us with its dependence on the linear system size L aswhere µ and K are shear and bulk moduli, σ 0 is the particle radius, and c is the velocity of sound. Such fluctuation is the source of the size-dependent behavior of 2D solids undergoing melting...

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From cage-jump motion to macroscopic diffusion in supercooled liquids

Cited by 56 publications

References 47 publications

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

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

Unveiling Dimensionality Dependence of Glassy Dynamics: 2D Infinite Fluctuation Eclipses Inherent Structural Relaxation

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