This title appears in the Scientific Report :
2016
Please use the identifier:
http://hdl.handle.net/2128/11192 in citations.
Please use the identifier: http://dx.doi.org/10.1103/PhysRevE.93.052607 in citations.
Heterogeneous diffusion, viscosity, and the Stokes-Einstein relation in binary liquids
Heterogeneous diffusion, viscosity, and the Stokes-Einstein relation in binary liquids
We investigate the origin of the breakdown of the Stokes-Einstein relation (SER) between diffusivity and viscosity in undercooled melts. A binary Lennard-Jones system, as a model for a metallic melt, is studied by molecular dynamics. A weak breakdown at high temperatures can be understood from the c...
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Personal Name(s): | Schober, H. R. (Corresponding author) |
---|---|
Peng, H. L. | |
Contributing Institute: |
JARA - HPC; JARA-HPC Theoretische Nanoelektronik; PGI-2 |
Published in: | Physical Review E Physical review / E, 93 93 (2016 2016) 5 5, S. 052607 052607 |
Imprint: |
College Park, Md.
APS
2016
2016-05-16 2016-05-01 |
PubMed ID: |
27300951 |
DOI: |
10.1103/PhysRevE.93.052607 |
Document Type: |
Journal Article |
Research Program: |
Dynamik in Gläsern und unterkühlten Schmelzen und Flüssigkeiten Controlling Collective States |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1103/PhysRevE.93.052607 in citations.
We investigate the origin of the breakdown of the Stokes-Einstein relation (SER) between diffusivity and viscosity in undercooled melts. A binary Lennard-Jones system, as a model for a metallic melt, is studied by molecular dynamics. A weak breakdown at high temperatures can be understood from the collectivization of motion, seen in the isotope effect. The strong breakdown at lower temperatures is connected to an increase in dynamic heterogeneity. On relevant time scales some particles diffuse much faster than the average or than predicted by the SER. The van Hove self-correlation function allows one to unambiguously identify slow particles. Their diffusivity is even less than predicted by the SER. The time span of these particles being slow particles, before their first conversion to be a fast one, is larger than the decay time of the stress correlation. The contribution of the slow particles to the viscosity rises rapidly upon cooling. Not only the diffusion but also the viscosity shows a dynamically heterogeneous scenario. We can define a “slow” viscosity. The SER is recovered as the relation between slow diffusivity and slow viscosity. |