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Decoupled length scales for diffusivity and viscosity in glass-forming liquids

Peng, H. L. and Voigtmann, Th. (2016) Decoupled length scales for diffusivity and viscosity in glass-forming liquids. Physical Review E, 94, 042612. American Physical Society. DOI: 10.1103/PhysRevE.94.042612 ISSN 1539-3755

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Abstract

The growth of the characteristic length scales both for diffusion and viscosity is investigated by molecular dynamics utilizing the finite-size effect in a binary Lennard-Jones mixture. For those quantities relevant to the diffusion process (e.g., the hydrodynamic value and the spatial correlation function), a strong system-size dependence is found. In contrast, it is weak or absent for the shear relaxation process. Correlation lengths are estimated from the decay of the spatial correlation functions. We find the length scale for viscosity decouples from the one of diffusivity, featured by a saturated length even in high supercooling. This temperature-independent behavior of the length scale is reminiscent of the unapparent structure change upon supercooling, implying the manifestation of configuration entropy. Whereas for the diffusion process, it is manifested by relaxation dynamics and dynamic heterogeneity. The Stokes-Einstein relation is found to break down at the temperature where the decoupling of these lengths happens.

Item URL in elib:https://elib.dlr.de/110081/
Document Type:Article
Title:Decoupled length scales for diffusivity and viscosity in glass-forming liquids
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Peng, H. L.hailong.peng (at) dlr.deUNSPECIFIED
Voigtmann, Th.thomas.voigtmann (at) dlr.deUNSPECIFIED
Date:2016
Journal or Publication Title:Physical Review E
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
Volume:94
DOI :10.1103/PhysRevE.94.042612
Page Range:042612
Publisher:American Physical Society
ISSN:1539-3755
Status:Published
Keywords:glass transition, Stokes-Einstein relation, diffusion, viscosity
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Vorhaben Materialwissenschaftliche Forschung (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Physics in Space
Deposited By: Voigtmann, Dr.rer.nat. Thomas
Deposited On:02 Jan 2017 07:14
Last Modified:10 Jan 2019 15:49

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