Structural properties of hockey stick-shaped particles in two dimensions

Martínez‐González, José A.; Varga, Szabolcs; Gurin, Péter; Quintana-H, Jacqueline

doi:10.1016/j.molliq.2012.11.020

Cited by 7 publications

(13 citation statements)

References 24 publications

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“…The modulated-nematic phase identified here differs from the bent nematic phase formed by V-shaped molecules 47,74 because the latter does not present a fully developed periodicity. Most likely, this difference is geometrical in origin and may be due to the missing central molecular segment in the V-shaped molecules.…”

Section: Modulated-nematic Phasementioning

confidence: 72%

“…Bow-shaped molecules instead arrange in an anti-ferromorphic smectic-A structure, wherein the polar vectorv adopts an opposite orientation in adjacent layers. This unusual ordering can be rationalized by extending a packing argument developed for the anti-ferroelectric ordering of V-shaped molecules, 47,74 i.e., for b = 0. 46 Because the excluded area of two molecules is smaller in the anti-parallel (v (i) = −v ( j) ) than in the parallel (v (i) =v ( j) ) arrangement, the former is entropically favored.…”

Section: B Quasi-nematic-smectic Transitionmentioning

confidence: 88%

“…Because this arrangement involves structural correlations between more than two molecules, it is not surprising that Onsager theory, which only takes into account two-particle correlations dramatically fails. Since many-particles correlation is also present in the modulated-nematic phase, we did not include the splay-bend deformation 47,74 in our Onsager theory calculation.…”

Section: Phase Diagramsmentioning

confidence: 99%

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

Tavarone

Stark

2015

The Journal of Chemical Physics

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We perform extensive Monte Carlo simulations of a two-dimensional bent hard-needle model in both its chiral zig-zag and its achiral bow-shape configurations and present their phase diagrams. We find evidence for a variety of stable phases: isotropic, quasi-nematic, smectic-C, anti-ferromorphic smectic-A, and modulated-nematic. This last phase consists of layers formed by supramolecular arches. They create a modulation of the molecular polarity whose period is sensitively controlled by molecular geometry. We identify transition densities using correlation functions together with appropriately defined order parameters and compare them with predictions from Onsager theory. The contribution of the molecular excluded area to deviations from Onsager theory and simple liquid crystal phase morphology is discussed. We demonstrate the isotropic-quasi-nematic transition to be consistent with a Kosterlitz-Thouless disclination unbinding scenario. C 2015 AIP Publishing LLC. [http://dx

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Section: Modulated-nematic Phasementioning

confidence: 72%

Section: B Quasi-nematic-smectic Transitionmentioning

confidence: 88%

Section: Phase Diagramsmentioning

confidence: 99%

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

Tavarone

Stark

2015

The Journal of Chemical Physics

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“…Using scanning tunneling microscopy (STM) the authors observed here several antiferroelectric chiral and nonchiral lamellar structures. Antiferroelectric smectic order in dense 2D banana systems has been also discussed theoretically as prevailing in [29] by Bisi et al based on the packing arguments and, later, by Gonzales et al in the case of needle-like, infinitely thin boomerangs [30] and hockey stick-shaped molecules consisting of two line segments [31]. It has been also detected in zero-thickness zig-zag and bow-shaped systems [26].…”

Section: Introductionmentioning

confidence: 91%

“…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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