Pressure, alignment and phase behavior of a simple model liquid crystal. A Monte Carlo simulation study

Steuer, Haiko; Hess, Siegfried; Schoen, Martin

doi:10.1016/s0378-4371(03)00547-8

Cited by 29 publications

(30 citation statements)

References 29 publications

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“…The model has been demonstrated subsequently [19,32–38] to be capable of reproducing properties of liquid crystals in a variety of contexts, ranging from the formation of nematic phases [32–35] to the development of defect topologies arising near the surface of spherical colloidal particles immersed in a nematic liquid-crystal host phase [19]. The introduction of chirality through the pseudoscalar on the far right side of Equation (4) follows in spirit a suggestion by Memmer et al [27] for the classical Gay-Berne model [39].…”

Section: The Modelmentioning

confidence: 99%

Nanoconfinement-Induced Structures in Chiral Liquid Crystals

Melle

Theile

Hall

et al. 2013

IJMS

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We employ Monte Carlo simulations in a specialized isothermal-isobaric and in the grand canonical ensemble to study structure formation in chiral liquid crystals as a function of molecular chirality. Our model potential consists of a simple Lennard-Jones potential, where the attractive contribution has been modified to represent the orientation dependence of the interaction between a pair of chiral liquid-crystal molecules. The liquid crystal is confined between a pair of planar and atomically smooth substrates onto which molecules are anchored in a hybrid fashion. Hybrid anchoring allows for the formation of helical structures in the direction perpendicular to the substrate plane without exposing the helix to spurious strains. At low chirality, we observe a cholesteric phase, which is transformed into a blue phase at higher chirality. More specifically, by studying the unit cell and the spatial arrangement of disclination lines, this blue phase can be established as blue phase II. If the distance between the confining substrates and molecular chirality are chosen properly, we see a third structure, which may be thought of as a hybrid, exhibiting mixed features of a cholesteric and a blue phase.

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Section: The Modelmentioning

confidence: 99%

Nanoconfinement-Induced Structures in Chiral Liquid Crystals

Melle

Theile

Hall

et al. 2013

IJMS

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“…Even though the aspect ratio of the mesogens is rather small in comparison with typical experimental systems we have chosen these numbers for reasons of comparison with earlier work. 25,26 Moreover, Hess and Su determined the bulk phase diagram for the present system at mean-field level which serves as a good orientation for selecting thermodynamic states in this work. 24 In particular, their results show that at the present temperature thermodynamically stable gas phases are characterized by nearly vanishing density.…”

Section: A Numerical Detailsmentioning

confidence: 99%

“…25,26 Using this potential Steuer et al 25 considered confined liquid crystal phases employing two anchoring scenarios: one in which no particular orientation of the mesogens is energetically preferred by the substrates (isotropic or nonspecific anchoring) and one representing a mesoscopic twisted nematic cell. However, the main focus of these earlier works 25,26 was on the formation of smectic phases in confinement. As we shall demonstrate below the exposure of the mesogens to surface fields favoring a specific anchoring may result in subtle structural changes very similar to those recently reported by Jordanovic and Klapp for dipolar fluids exposed to external magnetic fields.…”

Section: Introductionmentioning

confidence: 99%

Isotropic–nematic phase transitions in confined mesogenic fluids. The role of substrate anchoring

2010

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The anchoring of rodlike liquid-crystalline molecules at solid surfaces plays an important role in the design of novel nanotechnological devices such as, for example, biosensors. In this work we investigate the impact of various anchoring scenarios on the isotropic-nematic phase transition of weakly anisometric, prolate mesogens confined to a mesoscopic slit-pore. We employ isostress ensemble Monte Carlo simulations in which the isotropic-nematic transition is driven by applying an external stress in the direction parallel to the substrate plane. The fluid-fluid interaction is described by a Lennard-Jones potential with an orientation-dependent attractive term. Our simulations show that different anchoring scenarios may shift the isotropic-nematic phase transition considerably. We locate this transition through response functions such as an isostress heat capacity, isothermal compressibility, and the Maier-Saupe order parameter. Our results suggest that for the present model system the isotropicnematic transition is likely to be continuous. For the planar anchoring scenario we observe the formation of a new layer of fluid molecules during a structural transformation preceding the isotropicnematic transition.

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“…The model used in this study is based on the CG LCDr of [38] but makes use of a recently published anisotropic potential, developed by Lintuvuori and Wilson [40], which, in turn, has its origins in the potential of Steuer et al [46]. Schematically, the model is shown in left frame of figure 1.…”

Section: Modelling and Computational Detailsmentioning

confidence: 99%

Simulation of bulk phases formed by polyphilic liquid crystal dendrimers

Ilnytskyi¹,

Lintuvuori²,

Wilson³

2010

Condens. Matter Phys.

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A coarse-grained simulation model for a third generation liquid crystalline dendrimer (LCDr) is presented. It allows, for the first time, for a successful molecular simulation study of a relation between the shape of a polyphilic macromolecular mesogen and the symmetry of a macroscopic phase. The model dendrimer consists of a soft central sphere and 32 grafted chains each terminated by a mesogen group. The mesogenic pair interactions are modelled by the recently proposed soft core spherocylinder model of Lintuvuori and Wilson [J. Chem. Phys, 128, 044906, (2008)]. Coarse-grained (CG) molecular dynamics (MD) simulations are performed on a melt of 100 molecules in the anisotropic-isobaric ensemble. The model LCDr shows conformational bistability, with both rod-like and disc-like conformations stable at lower temperatures. Each conformation can be induced by an external aligning field of appropriate symmetry that acts on the mesogens (uniaxial for rod-like and planar for disc-like), leading to formation of a monodomain smectic A (Sm A ) or a columnar (Col) phase, respectively. Both phases are stable for approximately the same temperature range and both exhibit a sharp transition to an isotropic cubic-like phase upon heating. We observe a very strong coupling between the conformation of the LCDr and the symmetry of a bulk phase, as suggested previously by theory. The study reveals rich potential in terms of the application of this form of CG modelling to the study of molecular self-assembly of liquid crystalline macromolecules.

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Pressure, alignment and phase behavior of a simple model liquid crystal. A Monte Carlo simulation study

Cited by 29 publications

References 29 publications

Nanoconfinement-Induced Structures in Chiral Liquid Crystals

Nanoconfinement-Induced Structures in Chiral Liquid Crystals

Isotropic–nematic phase transitions in confined mesogenic fluids. The role of substrate anchoring

Simulation of bulk phases formed by polyphilic liquid crystal dendrimers

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