A study of steric chirality: the chiral nematic phase of a system of chiral two-site HGO molecules

Varga, Szabolcs; Jackson, George

doi:10.1080/00268976.2011.556577

Cited by 11 publications

(16 citation statements)

References 108 publications

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“…The binodal coexistence concentrations can then be obtained by equating Eqs. (47) and (48) in the two phases and solving the resulting set of coupled equations via a relaxed multivariate Newton-Raphson scheme, 100 using the uniform limit of the ODF for the isotropic phase,…”

Section: A the Isotropic-cholesteric Phase Transitionmentioning

confidence: 99%

Perturbative density functional methods for cholesteric liquid crystals

Tortora

Doye

2017

The Journal of Chemical Physics

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We introduce a comprehensive numerical framework to generically infer the emergent macroscopic properties of uniaxial nematic and cholesteric phases from that of their microscopic constituent mesogens. This approach, based on the full numerical resolution of the Poniewierski-Stecki equations in the weak chirality limit, may expediently handle a wide range of particle models through the use of Monte-Carlo sampling for all virial-type integrals. Its predictions in terms of equilibrium cholesteric structures are found to be in excellent agreement with previous full-functional descriptions, thereby demonstrating the quantitative validity of the perturbative treatment of chirality for pitch lengths as short as a few dozen particle diameters. Furthermore, the use of the full angle-dependent virial coefficients in the Onsager-Parsons-Lee formalism increases its numerical efficiency by several orders of magnitude over that of these previous methods. The comparison of our results with numerical simulations however reveals some shortcomings of the Parsons-Lee approximation for systems of strongly non-convex particles, notwithstanding the accurate inclusion of their full effective molecular volume. Further potential limitations of our theory in terms of phase symmetry assumptions are also examined, and prospective directions for future improvements discussed

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Section: A the Isotropic-cholesteric Phase Transitionmentioning

confidence: 99%

Perturbative density functional methods for cholesteric liquid crystals

Tortora

Doye

2017

The Journal of Chemical Physics

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“…A fundamental open question regards the relationship between macroscopic and microscopic chirality, i.e., between the handedness of the phase and that of the constituent particles [14][15][16][17]. Moreover, it is still to be unambiguously proved that hard chiral interactions alone can give rise to an entropy-stabilized…”

mentioning

confidence: 99%

“…(b) Hard helix particle modeled as a collection of 15 partially overlapping hard spheres of diameter σ, whose centers of mass are equally spaced on a right-handed helix of contour length L = 10 σ, inner radius r = 0.4 σ and pitch p = 4 σ [18]. The orientation of the helix can be expressed by means of the unit vectorω and the internal azimuthal angle α. chiral-nematic phase [17,18]. The problem in interpreting experimental data is largely due to the limitations of theory and simulation methods.…”

mentioning

confidence: 99%

Density functional theory for chiral nematic liquid crystals

et al. 2014

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Even though chiral nematic phases were the first liquid crystals experimentally observed more than a century ago, the origin of the thermodynamic stability of cholesteric states is still unclear. In this Letter we address the problem by means of a novel density functional theory for the equilibrium pitch of chiral particles. When applied to right-handed hard helices, our theory predicts an entropydriven cholesteric phase, which can be either right-or left-handed, depending not only on the particle shape but also on the thermodynamic state. We explain the origin of the chiral ordering as an interplay between local nematic alignment and excluded-volume differences between left-and right-handed particle pairs.PACS numbers: 64.70.mf, 64.70.pv, 61.30.Cz, 61.30.St Cholesteric phases, also known as chiral nematics, are fascinating examples of liquid crystals. Liquid crystals are phases of matter characterized by a degree of spontaneous breaking of the rotational and translational symmetries that is higher than in the liquid and lower than in the crystal phase. In the nematic phase, for example, the particles self-organize by all aligning along a common direction (the nematic director), while keeping their centers of mass homogeneously distributed in space. Chiral nematic liquid crystals are peculiar as their nematic director rotates like a helix around a chiral director, thus giving rise to a chiral distribution of the orientations of the particles [1]. A cholesteric phase can be either righthanded (as in Fig. 1(a)) or left-handed, depending on the handedness of the helix drawn by the nematic directorn. The wavelength associated to a full rotation of the nematic director around the chiral directorχ is known as the cholesteric pitch P . Cholesteric phases are commonly found in both thermotropic molecular compounds (e.g., derivatives of cholesterol [2][3][4][5]) and in lyotropic colloidal suspensions of, e.g., DNA [6,7] and filamentous viruses [8][9][10][11][12]. Their widespread occurrence explains why cholesterics were the first liquid-crystal phase experimentally observed [2]. The pitch is experimentally known to take values several orders of magnitude higher than the size of the constituent particles, reaching the visible-light wavelength in molecular compounds. For this reason, and for their liquid-like rheological properties, cholesterics have long found wide technological application in the opto-electronic industry [13].Despite their long history and widespread technological applications, surprisingly little is understood about this chiral state of matter. A fundamental open question regards the relationship between macroscopic and microscopic chirality, i.e., between the handedness of the phase and that of the constituent particles [14][15][16][17]. Moreover, it is still to be unambiguously proved that hard chiral interactions alone can give rise to an entropy-stabilized chiral-nematic phase [17,18]. The problem in interpreting experimental data is largely due to the limitations of theory and simulation method...

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“…He has also established an international reputation in the area of liquid crystal modelling [12][13][14][15][16][17][18][19]. George has published 39 papers in Molecular Physics, his recent work being illustrated in references [20][21][22][23][24][25].…”

Section: Announcement Of a New Editormentioning

confidence: 99%

Announcement of a new editor

2013

Molecular Physics

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A study of steric chirality: the chiral nematic phase of a system of chiral two-site HGO molecules

Cited by 11 publications

References 108 publications

Perturbative density functional methods for cholesteric liquid crystals

Perturbative density functional methods for cholesteric liquid crystals

Density functional theory for chiral nematic liquid crystals

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