A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems

A bidimensional (2D) thermotropic liquid crystal (LC) is investigated with Molecular Dynamics (MD) simulations. The Gay-Berne mesogen with parameterization GB(3, 5, 2, 1) is used to model a calamitic system. Spatial orientation of the LC samples is probed with the nematic order parameter: a sharp is...

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Main Authors: A. Calderón-Alcaraz, J. Munguía-Valadez, S. I. Hernández, A. Ramírez-Hernández, E. J. Sambriski, J. A. Moreno-Razo
Format: Article
Language:English
Published: Frontiers Media S.A. 2021-03-01
Series:Frontiers in Physics
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fphy.2020.622872/full
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spelling doaj-2ffaef9731784b0ea7c04660aede23132021-03-02T15:27:44ZengFrontiers Media S.A.Frontiers in Physics2296-424X2021-03-01810.3389/fphy.2020.622872622872A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined SystemsA. Calderón-Alcaraz0J. Munguía-Valadez1S. I. Hernández2A. Ramírez-Hernández3E. J. Sambriski4J. A. Moreno-Razo5Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, MexicoDepartamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, MexicoUnidad Multidisciplinaria de Docencia e Investigación-Juriquilla, Facultad de Ciencias, Universidad Nacional Autónoma de México, Juriquilla, Querétaro, MexicoDepartment of Biomedical Engineering and Chemical Engineering, and Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX, United StatesDepartment of Chemistry, Delaware Valley University, Doylestown, PA, United StatesDepartamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, Mexico City, MexicoA bidimensional (2D) thermotropic liquid crystal (LC) is investigated with Molecular Dynamics (MD) simulations. The Gay-Berne mesogen with parameterization GB(3, 5, 2, 1) is used to model a calamitic system. Spatial orientation of the LC samples is probed with the nematic order parameter: a sharp isotropic-smectic (I-Sm) transition is observed at lower pressures. At higher pressures, the I-Sm transition involves an intermediate nematic phase. Topology of the orthobaric phase diagram for the 2D case differs from the 3D case in two important respects: 1) the nematic region appears at lower temperatures and slightly lower densities, and 2) the critical point occurs at lower temperature and slightly higher density. The 2D calamitic model is used to probe the structural behavior of LC samples under strong confinement when either planar or homeotropic anchoring prevails. Samples subjected to circular, square, and triangular boundaries are gradually cooled to study how orientational order emerges. Depending on anchoring mode and confining geometry, characteristic topological defects emerge. Textures in these systems are similar to those observed in experiments and simulations of lyotropic LCs.https://www.frontiersin.org/articles/10.3389/fphy.2020.622872/fullconfinementtopologicaldisclinationtransitionnematicsimulation
collection DOAJ
language English
format Article
sources DOAJ
author A. Calderón-Alcaraz
J. Munguía-Valadez
S. I. Hernández
A. Ramírez-Hernández
E. J. Sambriski
J. A. Moreno-Razo
spellingShingle A. Calderón-Alcaraz
J. Munguía-Valadez
S. I. Hernández
A. Ramírez-Hernández
E. J. Sambriski
J. A. Moreno-Razo
A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
Frontiers in Physics
confinement
topological
disclination
transition
nematic
simulation
author_facet A. Calderón-Alcaraz
J. Munguía-Valadez
S. I. Hernández
A. Ramírez-Hernández
E. J. Sambriski
J. A. Moreno-Razo
author_sort A. Calderón-Alcaraz
title A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
title_short A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
title_full A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
title_fullStr A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
title_full_unstemmed A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
title_sort bidimensional gay-berne calamitic fluid: structure and phase behavior in bulk and strongly confined systems
publisher Frontiers Media S.A.
series Frontiers in Physics
issn 2296-424X
publishDate 2021-03-01
description A bidimensional (2D) thermotropic liquid crystal (LC) is investigated with Molecular Dynamics (MD) simulations. The Gay-Berne mesogen with parameterization GB(3, 5, 2, 1) is used to model a calamitic system. Spatial orientation of the LC samples is probed with the nematic order parameter: a sharp isotropic-smectic (I-Sm) transition is observed at lower pressures. At higher pressures, the I-Sm transition involves an intermediate nematic phase. Topology of the orthobaric phase diagram for the 2D case differs from the 3D case in two important respects: 1) the nematic region appears at lower temperatures and slightly lower densities, and 2) the critical point occurs at lower temperature and slightly higher density. The 2D calamitic model is used to probe the structural behavior of LC samples under strong confinement when either planar or homeotropic anchoring prevails. Samples subjected to circular, square, and triangular boundaries are gradually cooled to study how orientational order emerges. Depending on anchoring mode and confining geometry, characteristic topological defects emerge. Textures in these systems are similar to those observed in experiments and simulations of lyotropic LCs.
topic confinement
topological
disclination
transition
nematic
simulation
url https://www.frontiersin.org/articles/10.3389/fphy.2020.622872/full
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