Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.

Detalhes bibliográficos
Autor(a) principal: Salcedo, Evy
Data de Publicação: 2011
Outros Autores: Oliveira, Alan Barros de, Barraz Júnior, Ney Marçal, Chakravarty, Charusita, Barbosa, Márcia Cristina Bernardes
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Institucional da UFOP
dARK ID: ark:/61566/001300000dc6s
Texto Completo: http://www.repositorio.ufop.br/handle/123456789/1465
Resumo: Molecular dynamics simulations are used to examine the relationship between water-like anomalies and the liquid-liquid critical point in a family of model fluids with multi-Gaussian, core-softened pair interactions. The core-softened pair interactions have two length scales, such that the longer length scale associated with a shallow, attractive well is kept constant while the shorter length scale associated with the repulsive shoulder is varied from an inflection point to a minimum of progressively increasing depth. The maximum depth of the shoulder well is chosen so that the resulting potential reproduces the oxygen-oxygen radial distribution function of the ST4 model of water. As the shoulder well depth increases, the pressure required to form the high density liquid decreases and the temperature up to which the high-density liquid is stable increases, resulting in the shift of the liquid-liquid critical point to much lower pressures and higher temperatures. To understand the entropic effects associated with the changes in the interaction potential, the pair correlation entropy is computed to show that the excess entropy anomaly diminishes when the shoulder well depth increases. Excess entropy scaling of diffusivity in this class of fluids is demonstrated, showing that decreasing strength of the excess entropy anomaly with increasing shoulder depth results in the progressive loss of water-like thermodynamic, structural and transport anomalies. Instantaneous normal mode analysis was used to index the overall curvature distribution of the fluid and the fraction of imaginary frequency modes was shown to correlate well with the anomalous behavior of the diffusivity and the pair correlation entropy. The results suggest in the case of core-softened potentials, in addition to the presence of two length scales, energetic, and entropic effects associated with local minima and curvatures of the pair interaction play an important role in determining the presence of water-like anomalies and the liquid-liquid phase transition.
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spelling Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.Molecular dynamics simulations are used to examine the relationship between water-like anomalies and the liquid-liquid critical point in a family of model fluids with multi-Gaussian, core-softened pair interactions. The core-softened pair interactions have two length scales, such that the longer length scale associated with a shallow, attractive well is kept constant while the shorter length scale associated with the repulsive shoulder is varied from an inflection point to a minimum of progressively increasing depth. The maximum depth of the shoulder well is chosen so that the resulting potential reproduces the oxygen-oxygen radial distribution function of the ST4 model of water. As the shoulder well depth increases, the pressure required to form the high density liquid decreases and the temperature up to which the high-density liquid is stable increases, resulting in the shift of the liquid-liquid critical point to much lower pressures and higher temperatures. To understand the entropic effects associated with the changes in the interaction potential, the pair correlation entropy is computed to show that the excess entropy anomaly diminishes when the shoulder well depth increases. Excess entropy scaling of diffusivity in this class of fluids is demonstrated, showing that decreasing strength of the excess entropy anomaly with increasing shoulder depth results in the progressive loss of water-like thermodynamic, structural and transport anomalies. Instantaneous normal mode analysis was used to index the overall curvature distribution of the fluid and the fraction of imaginary frequency modes was shown to correlate well with the anomalous behavior of the diffusivity and the pair correlation entropy. The results suggest in the case of core-softened potentials, in addition to the presence of two length scales, energetic, and entropic effects associated with local minima and curvatures of the pair interaction play an important role in determining the presence of water-like anomalies and the liquid-liquid phase transition.2012-09-28T14:00:32Z2012-09-28T14:00:32Z2011info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfSALCEDO, E. et al. Core-softened fluids, water-like anomalies, and the liquid-liquid critical points. The Journal of Chemical Physics, v. 135, n. 4, p. 044517, 2011. Disponível em: <http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000135000004044517000001&idtype=cvips&doi=10.1063/1.3613669&prog=normal>. Acesso em: 28 set. 2012.10897690http://www.repositorio.ufop.br/handle/123456789/1465ark:/61566/001300000dc6sO periódico The Journal of Chemical Physics concede permissão para depósito do artigo no Repositório Institucional da UFOP. Número da licença: 3343110191972.info:eu-repo/semantics/openAccessSalcedo, EvyOliveira, Alan Barros deBarraz Júnior, Ney MarçalChakravarty, CharusitaBarbosa, Márcia Cristina Bernardesengreponame:Repositório Institucional da UFOPinstname:Universidade Federal de Ouro Preto (UFOP)instacron:UFOP2024-11-11T01:15:28Zoai:repositorio.ufop.br:123456789/1465Repositório InstitucionalPUBhttp://www.repositorio.ufop.br/oai/requestrepositorio@ufop.edu.bropendoar:32332024-11-11T01:15:28Repositório Institucional da UFOP - Universidade Federal de Ouro Preto (UFOP)false
dc.title.none.fl_str_mv Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
title Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
spellingShingle Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
Salcedo, Evy
title_short Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
title_full Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
title_fullStr Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
title_full_unstemmed Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
title_sort Core-softened fluids, water-like anomalies, and the liquid-liquid critical points.
author Salcedo, Evy
author_facet Salcedo, Evy
Oliveira, Alan Barros de
Barraz Júnior, Ney Marçal
Chakravarty, Charusita
Barbosa, Márcia Cristina Bernardes
author_role author
author2 Oliveira, Alan Barros de
Barraz Júnior, Ney Marçal
Chakravarty, Charusita
Barbosa, Márcia Cristina Bernardes
author2_role author
author
author
author
dc.contributor.author.fl_str_mv Salcedo, Evy
Oliveira, Alan Barros de
Barraz Júnior, Ney Marçal
Chakravarty, Charusita
Barbosa, Márcia Cristina Bernardes
description Molecular dynamics simulations are used to examine the relationship between water-like anomalies and the liquid-liquid critical point in a family of model fluids with multi-Gaussian, core-softened pair interactions. The core-softened pair interactions have two length scales, such that the longer length scale associated with a shallow, attractive well is kept constant while the shorter length scale associated with the repulsive shoulder is varied from an inflection point to a minimum of progressively increasing depth. The maximum depth of the shoulder well is chosen so that the resulting potential reproduces the oxygen-oxygen radial distribution function of the ST4 model of water. As the shoulder well depth increases, the pressure required to form the high density liquid decreases and the temperature up to which the high-density liquid is stable increases, resulting in the shift of the liquid-liquid critical point to much lower pressures and higher temperatures. To understand the entropic effects associated with the changes in the interaction potential, the pair correlation entropy is computed to show that the excess entropy anomaly diminishes when the shoulder well depth increases. Excess entropy scaling of diffusivity in this class of fluids is demonstrated, showing that decreasing strength of the excess entropy anomaly with increasing shoulder depth results in the progressive loss of water-like thermodynamic, structural and transport anomalies. Instantaneous normal mode analysis was used to index the overall curvature distribution of the fluid and the fraction of imaginary frequency modes was shown to correlate well with the anomalous behavior of the diffusivity and the pair correlation entropy. The results suggest in the case of core-softened potentials, in addition to the presence of two length scales, energetic, and entropic effects associated with local minima and curvatures of the pair interaction play an important role in determining the presence of water-like anomalies and the liquid-liquid phase transition.
publishDate 2011
dc.date.none.fl_str_mv 2011
2012-09-28T14:00:32Z
2012-09-28T14:00:32Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv SALCEDO, E. et al. Core-softened fluids, water-like anomalies, and the liquid-liquid critical points. The Journal of Chemical Physics, v. 135, n. 4, p. 044517, 2011. Disponível em: <http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000135000004044517000001&idtype=cvips&doi=10.1063/1.3613669&prog=normal>. Acesso em: 28 set. 2012.
10897690
http://www.repositorio.ufop.br/handle/123456789/1465
dc.identifier.dark.fl_str_mv ark:/61566/001300000dc6s
identifier_str_mv SALCEDO, E. et al. Core-softened fluids, water-like anomalies, and the liquid-liquid critical points. The Journal of Chemical Physics, v. 135, n. 4, p. 044517, 2011. Disponível em: <http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JCPSA6000135000004044517000001&idtype=cvips&doi=10.1063/1.3613669&prog=normal>. Acesso em: 28 set. 2012.
10897690
ark:/61566/001300000dc6s
url http://www.repositorio.ufop.br/handle/123456789/1465
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositório Institucional da UFOP
instname:Universidade Federal de Ouro Preto (UFOP)
instacron:UFOP
instname_str Universidade Federal de Ouro Preto (UFOP)
instacron_str UFOP
institution UFOP
reponame_str Repositório Institucional da UFOP
collection Repositório Institucional da UFOP
repository.name.fl_str_mv Repositório Institucional da UFOP - Universidade Federal de Ouro Preto (UFOP)
repository.mail.fl_str_mv repositorio@ufop.edu.br
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