Fickian crossover and length scales from two point functions in supercooled liquids
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Data de Publicação: | 2006 |
Outros Autores: | |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/205008 |
Resumo: | Particle motion of a Lennard-Jones supercooled liquid near the glass transition is studied by molecular dynamics simulations. We analyze the wave vector dependence of relaxation times in the incoherent self-scattering function and show that at least three different regimes can be identified and its scaling properties determined. The transition from one regime to another happens at characteristic length scales. The length scale associated with the onset of Fickian diffusion corresponds to the maximum size of heterogeneities in the system, and the characteristic time scale is several times larger than the alpha relaxation time. A second crossover length scale is observed, which corresponds to the typical time and length of heterogeneities, in agreement with results from four point functions. The different regimes can be traced back to the behavior of the van Hove distribution of displacements, which shows a characteristic exponential regime in the heterogeneous region before the crossover to Gaussian diffusion and should be observable in experiments. Our results show that it is possible to obtain characteristic length scales of heterogeneities through the computation of two point functions at different times. |
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Stariolo, Daniel AdrianFabricius, Gabriel2020-01-28T04:12:10Z20060021-9606http://hdl.handle.net/10183/205008000556798Particle motion of a Lennard-Jones supercooled liquid near the glass transition is studied by molecular dynamics simulations. We analyze the wave vector dependence of relaxation times in the incoherent self-scattering function and show that at least three different regimes can be identified and its scaling properties determined. The transition from one regime to another happens at characteristic length scales. The length scale associated with the onset of Fickian diffusion corresponds to the maximum size of heterogeneities in the system, and the characteristic time scale is several times larger than the alpha relaxation time. A second crossover length scale is observed, which corresponds to the typical time and length of heterogeneities, in agreement with results from four point functions. The different regimes can be traced back to the behavior of the van Hove distribution of displacements, which shows a characteristic exponential regime in the heterogeneous region before the crossover to Gaussian diffusion and should be observable in experiments. Our results show that it is possible to obtain characteristic length scales of heterogeneities through the computation of two point functions at different times.application/pdfengThe journal of chemical physics. New York. Vol. 125, no. 6 (Aug. 2006), 064505, 7p.Transicao vitreaDinâmica molecularFickian crossover and length scales from two point functions in supercooled liquidsEstrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSTEXT000556798.pdf.txt000556798.pdf.txtExtracted Texttext/plain32124http://www.lume.ufrgs.br/bitstream/10183/205008/2/000556798.pdf.txt2b6d41cf6f254484bd6273a9508df734MD52ORIGINAL000556798.pdfTexto completo (inglês)application/pdf493322http://www.lume.ufrgs.br/bitstream/10183/205008/1/000556798.pdf20fc6fb942c9f7451f826fe795b29832MD5110183/2050082020-01-29 05:08:45.976508oai:www.lume.ufrgs.br:10183/205008Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2020-01-29T07:08:45Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
Fickian crossover and length scales from two point functions in supercooled liquids |
title |
Fickian crossover and length scales from two point functions in supercooled liquids |
spellingShingle |
Fickian crossover and length scales from two point functions in supercooled liquids Stariolo, Daniel Adrian Transicao vitrea Dinâmica molecular |
title_short |
Fickian crossover and length scales from two point functions in supercooled liquids |
title_full |
Fickian crossover and length scales from two point functions in supercooled liquids |
title_fullStr |
Fickian crossover and length scales from two point functions in supercooled liquids |
title_full_unstemmed |
Fickian crossover and length scales from two point functions in supercooled liquids |
title_sort |
Fickian crossover and length scales from two point functions in supercooled liquids |
author |
Stariolo, Daniel Adrian |
author_facet |
Stariolo, Daniel Adrian Fabricius, Gabriel |
author_role |
author |
author2 |
Fabricius, Gabriel |
author2_role |
author |
dc.contributor.author.fl_str_mv |
Stariolo, Daniel Adrian Fabricius, Gabriel |
dc.subject.por.fl_str_mv |
Transicao vitrea Dinâmica molecular |
topic |
Transicao vitrea Dinâmica molecular |
description |
Particle motion of a Lennard-Jones supercooled liquid near the glass transition is studied by molecular dynamics simulations. We analyze the wave vector dependence of relaxation times in the incoherent self-scattering function and show that at least three different regimes can be identified and its scaling properties determined. The transition from one regime to another happens at characteristic length scales. The length scale associated with the onset of Fickian diffusion corresponds to the maximum size of heterogeneities in the system, and the characteristic time scale is several times larger than the alpha relaxation time. A second crossover length scale is observed, which corresponds to the typical time and length of heterogeneities, in agreement with results from four point functions. The different regimes can be traced back to the behavior of the van Hove distribution of displacements, which shows a characteristic exponential regime in the heterogeneous region before the crossover to Gaussian diffusion and should be observable in experiments. Our results show that it is possible to obtain characteristic length scales of heterogeneities through the computation of two point functions at different times. |
publishDate |
2006 |
dc.date.issued.fl_str_mv |
2006 |
dc.date.accessioned.fl_str_mv |
2020-01-28T04:12:10Z |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/205008 |
dc.identifier.issn.pt_BR.fl_str_mv |
0021-9606 |
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000556798 |
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0021-9606 000556798 |
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http://hdl.handle.net/10183/205008 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
The journal of chemical physics. New York. Vol. 125, no. 6 (Aug. 2006), 064505, 7p. |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
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application/pdf |
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