Phase ordering of zig-zag and bow-shaped hard needles in two dimensions

Tavarone, Raffaele; Stark, Holger

doi:10.1063/1.4930886

Cited by 18 publications

(12 citation statements)

References 83 publications

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“…It has been also detected in zero-thickness zig-zag and bow-shaped systems [26]. In addition, in [26,30,31] the authors have observed that upon increasing pressure, before the system attains antiferroelectric smectic A phase, a spatially non-uniform, bend-deformed polar domains with the overall zero net polarization are being formed.…”

Section: Introductionmentioning

confidence: 91%

Structure formation in monolayers composed of hard bent-core molecules

et al. 2016

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Two-dimensional ensembles of bent-core shaped molecules attain at highly orienting surfaces liquid crystalline structures characteristic mostly for lamellar chiral or nonchiral antiferroelectric order. Here, using the Onsager-type of density functional theory supplemented by constant-pressure Monte-Carlo (MC) simulation we investigate the role of excluded-volume interactions in stabilizing different structures in monolayers filled with bent-shaped molecules. We study influence of molecular features, like the apex angle, thickness of the arm and the type of the arm edges on the stability of layered structures. For simple molecular shapes taken the observed phases are dominated by the lamellar antiferroelectric type as observed experimentally, but a considerable sensitivity of the ordering to details of the molecular shape is found for order parameters and wave vectors of the structures. Interestingly, for large opening angles and not too thick molecules a window of stable nematic splay-bend phase is shown to exist. The presented theory models equilibrium properties of bent-core liquid crystals subjected to strong planar anchoring, in the case when details of the surface are of secondary importance.

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Section: Introductionmentioning

confidence: 91%

Structure formation in monolayers composed of hard bent-core molecules

et al. 2016

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“…One of valuable tools in such studies are computer simulations, such as Monte Carlo sampling (MC) and Molecular Dynamics (MD), which have a long-standing tradition in the investigation of structural properties of LC phases using a diverse range of models ranging from simplified lattice systems to fully atomistic ones [29][30][31] . Generally, the anisotropic shape of BSMs can be approximated in the simulations either by V-like or C-like bent objects (reflecting the C 2v symmetry) composed of i.a., needles [32][33][34] , spheres [35][36][37][38] , or spherocylinders [39][40][41][42] . It has been shown that those systems, each one separately, produce a wealth of interesting nematic and smectic phases.…”

Section: Introductionmentioning

confidence: 99%

In silico study of liquid crystalline phases formed by bent-shaped molecules with excluded-volume type interactions

Kubala,

Tomczyk,

Cieśla

2021

Preprint

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We have numerically studied a liquid composed of achiral, bent-shaped molecules built of tangent spheres. The system is known to spontaneously break mirror symmetry, as it forms a macroscopically chiral, twist-bend nematic phase [Phys. Rev. Lett. 115, 147801 (2015)]. Here, we have examined full phase diagram of such liquid and observed several phases characterized by orientational and/or translational ordering of molecules. Apart from conventional nematic, smectic A, and the abovementioned twist-bend nematic phase, we have identified antiferroelectric smectic A phase. For large densities and high degree of molecule's structural bend, another smectic phase emerged, where the polarization vector rotates within a single smectic layer. These results were confirmed using both Monte Carlo and molecular dynamics simulations.

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“…In a previous work we have investigated the phase ordering of bent needles with varying shape. 29 Our work is motivated by a recent experimental study of Fang et al 1 on the glasslike orientational dynamics of a self-assembled monolayer of photo-switching molecules. After aligning the molecules with light, the authors observed the decay of orientational order (or birefringence) under either thermal erasure or erasure with circularly polarized (CP) light.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules on a surface

Tavarone

Stark

2016

The Journal of Chemical Physics

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Recent experiments have demonstrated that in a dense monolayer of photo-switchable dye methyl-red molecules the relaxation of an initial birefringence follows a power-law decay, typical for glass-like dynamics. The slow relaxation can efficiently be controlled and accelerated by illuminating the monolayer with circularly polarized light, which induces trans-cis isomerization cycles. To elucidate the microscopic mechanism, we develop a two-dimensional molecular model in which the trans and cis isomers are represented by straight and bent needles, respectively. As in the experimental system, the needles are allowed to rotate and to form overlaps but they cannot translate. The out-ofequilibrium rotational dynamics of the needles is generated using kinetic Monte Carlo simulations. We demonstrate that, in a regime of high density and low temperature, the power-law relaxation can be traced to the formation of spatio-temporal correlations in the rotational dynamics, i.e., dynamic heterogeneity. We also show that the nearly isotropic cis isomers can prevent dynamic heterogeneity from forming in the monolayer and that the relaxation then becomes exponential. C 2016 AIP Publishing LLC. [http://dx

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Phase ordering of zig-zag and bow-shaped hard needles in two dimensions

Cited by 18 publications

References 83 publications

Structure formation in monolayers composed of hard bent-core molecules

Structure formation in monolayers composed of hard bent-core molecules

In silico study of liquid crystalline phases formed by bent-shaped molecules with excluded-volume type interactions

Kinetic Monte Carlo simulations for birefringence relaxation of photo-switchable molecules on a surface

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