Exposing a dynamical signature of the freezing transition through the sound propagation gap

Martinez, Vincent A.; Zaccarelli, Emanuela; Sanz, Eduardo; Valeriani, Chantal; Megen, W. van

doi:10.1038/ncomms6503

Cited by 10 publications

(6 citation statements)

References 49 publications

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“…Further investigations can also be done by comparing our results for the current-current correlator to the velocity autocorrelation function measured by van Megen and coworkers (see e.g. [29,41]). Furthermore, we split the van Hove current in its adiabatic and superadiabatic contribution by employing the recently developed adiabatic construction for the test particle situation.…”

Section: Discussionmentioning

confidence: 72%

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Dynamic pair correlations and superadiabatic forces in a dense Brownian liquid

Schindler

Schmidt

2016

The Journal of Chemical Physics

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We study dynamic two-body correlation functions, i.e. the two-body density, the current-density correlator or van Hove current, and the current-current correlator in Brownian dynamics computer simulations of a dense Lennard-Jones bulk liquid. The dynamic decay of the correlation shells of the two-body density is examined in detail. Inner correlation shells decay faster than outer correlation shells, whereas outer correlation shells remain stable for increasing times. Within a dynamic test particle picture the mechanism is assumed to be triggered by the dislocation of the self particle, which releases the confinement of the surrounding correlation shells. We present a division of the van Hove current into an adiabatic and a superadiabatic contribution. The magnitude of the adiabatic van Hove current is found to exceed that of the total van Hove current, which is consistent with dynamic density functional theory overestimating the speed of the dynamics. The direction of the superadiabatic van Hove current opposes that of the total van Hove current. The current-current correlator reveals detailed insight in the collisions of the particles. We find a large static nearestneighbor peak, which results from colliding particles and different dynamic peaks, that are attributed to consecutive collisions.

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Section: Discussionmentioning

confidence: 72%

“…The Fourier transform of the longitudinal currentcurrent correlator is the velocity autocorrelation function [20]. Recently this function has been measured via the time derivative of the intermediate scattering function [29].…”

Section: Introductionmentioning

confidence: 99%

Dynamic pair correlations and superadiabatic forces in a dense Brownian liquid

Schindler

Schmidt

2016

The Journal of Chemical Physics

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“…4b ). The high-frequency phononic gap has recently been observed in the vicinity of the freezing point 24 . The emergence of high-q transverse phononic gaps in the liquid and supercritical states is an unexpected and surprising result in view of structural simplicity of monatomic liquid Ar.…”

Section: Resultsmentioning

confidence: 99%

Thermally triggered phononic gaps in liquids at THz scale

Bolmatov

Zhernenkov

Zav’yalov

et al. 2016

Sci Rep

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In this paper we present inelastic X-ray scattering experiments in a diamond anvil cell and molecular dynamic simulations to investigate the behavior of phononic excitations in liquid Ar. The spectra calculated using molecular dynamics were found to be in a good agreement with the experimental data. Furthermore, we observe that, upon temperature increases, a low-frequency transverse phononic gap emerges while high-frequency propagating modes become evanescent at the THz scale. The effect of strong localization of a longitudinal phononic mode in the supercritical phase is observed for the first time. The evidence for the high-frequency transverse phononic gap due to the transition from an oscillatory to a ballistic dynamic regimes of motion is presented and supported by molecular dynamics simulations. This transition takes place across the Frenkel line thermodynamic limit which demarcates compressed liquid and non-compressed fluid domains on the phase diagram and is supported by calculations within the Green-Kubo phenomenological formalism. These results are crucial to advance the development of novel terahertz thermal devices, phononic lenses, mirrors, and other THz metamaterials.

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“…For the hard sphere system this gap, centred on qm, first emerges at φ≈0.45 and disappears at φ≈φf 58 . Aside from being evident directly in sound dispersion curves, the occurrence of overdamping of sound is also evident in the manner of decay of the negative long time tail of the CAF 58 .…”

Section: A Identification Of Mechanisms E and C⇆e In Experimental Datamentioning

confidence: 99%

The cage effect in systems of hard spheres

Megen

Schöpe

2017

The Journal of Chemical Physics

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The cage effect is generally invoked when discussing the delay in the decay of time correlation functions of dense fluids. In an attempt to examine the role of caging more closely, we consider the spread of the displacement distributions of Brownian particles. These distributions are necessarily biased by the presence of neighbouring particles. Accommodation of this bias by those neighbours conserves the displacement distribution locally and presents a collective mechanism for exploring configuration space that is more efficient than the intrinsic Brownian motion. Caging of some particles incurs, through the impost of global conservation of the displacement distribution, a delayed, non-local collective process. This non-locality compromises the efficiency with which configuration space is explored. Both collective mechanisms incur delay or stretching of time correlation functions, in particular the particle number and flux densities. This paper identifies and distinguishes these mechanisms in existing data from experiments and computer simulations on systems of particles with hard sphere interactions.

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Exposing a dynamical signature of the freezing transition through the sound propagation gap

Cited by 10 publications

References 49 publications

Dynamic pair correlations and superadiabatic forces in a dense Brownian liquid

Dynamic pair correlations and superadiabatic forces in a dense Brownian liquid

Thermally triggered phononic gaps in liquids at THz scale

The cage effect in systems of hard spheres

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