A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
A Bidimensional Gay-Berne Calamitic Fluid: Structure and Phase Behavior in Bulk and Strongly Confined Systems
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DOI：
10.3389/fphy.2020.622872
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发表时间：
2021-03-02
影响因子：
3.1
通讯作者：
Moreno-Razo, J. A.
中科院分区：
文献类型：
--
作者：
Calderon-Alcaraz, A.;Munguia-Valadez, J.;Moreno-Razo, J. A.
用分子动力学方法研究了二维热致液晶（LC）。采用参数化GB（3,5,2,1）的Gay-Berne介观来模拟灾变系统。用向列序参数探测LC样品的空间取向：在较低压力下观察到尖锐的各向同性-近晶（I-Sm）转变。在较高的压力下，I-Sm转变包括一个中间的向列相。二维情况下的正压相图拓扑结构与三维情况有两个重要的不同之处：1)向列区出现在较低的温度和稍低的密度下，2)临界点出现在较低的温度和稍高的密度下。采用二维灾变模型研究了平面锚固和同向锚固两种锚固方式下LC试样在强约束条件下的结构行为。样品受到圆形，方形和三角形的边界逐渐冷却，以研究如何取向秩序出现。根据锚定模式和围合几何的不同，出现了特征性的拓扑缺陷。这些体系中的织构与在实验和模拟中观察到的lyotropic lc相似。
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.