Flexoelectric effects in liquid crystals formed by pear-shaped molecules. A computer simulation study

Stelzer, Joachim; Berardi, Roberto; Zannoni, Claudio

doi:10.1016/s0009-2614(98)01262-7

Cited by 27 publications

(26 citation statements)

References 32 publications

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“…Equivalent simulations by Billeter and Pelcovits [14], using qualitatively the same model but with different energy parametrisations and an alternative method for the calculation of the flexoelectric coefficients, confirmed the results of Ref. [13]. In this case, however, no stable nematic phase was found between the isotropic and (locally antiparallel) smectic A phases.…”

Section: Introductionsupporting

confidence: 77%

“…Subsequently, Stelzer et al [13] investigated the behaviour of pear-shaped molecules using a model with two interaction sites per particle; each particle comprised a Lennard-Jones site embedded near to one end of a Gay-Berne site. Isotropic, nematic and smectic phases were observed, local antiparallel alignment being seen in the nematic phase.…”

Section: Introductionmentioning

confidence: 99%

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Computer simulations of hard pear-shaped particles

et al. 2003

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We report results obtained from Monte Carlo simulations investigating mesophase formation in two model systems of hard pear-shaped particles. The first model considered is a hard variant of the truncated Stone-Expansion model previously shown to form nematic and smectic mesophases when embedded within a 12-6 Gay-Berne-like potential [1]. When stripped of its attractive interactions, however, this system is found to lose its liquid crystalline phases. For particles of length to breadth ratio k = 3, glassy behaviour is seen at high pressures, whereas for k = 5 several bi-layer-like domains are seen, with high intradomain order but little interdomain orientational correlation. For the second model, which uses a parametric shape parameter based on the generalised Gay-Berne formalism, results are presented for particles with elongation k = 3, 4 and 5. Here, the systems with k = 3 and 4 fail to display orientationally ordered phases, but that with k = 5 shows isotropic, nematic and, unusually for a hard-particle model, interdigitated smectic A 2 phases.2

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Section: Introductionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Computer simulations of hard pear-shaped particles

et al. 2003

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“…Experimentally, the determination of these quantities is highly non-trivial 29,30 , mainly due to the fact that the flexoelectric coefficients are not measured directly, but rather in linear combinations or as ratios involving elastic constants. In simulations, the flexoelectric coefficients of pear-shaped GayBerne ellipsoid/Lennard-Jones sphere molecules have been measured directly using expressions involving the direct correlation function 31 . The coefficients for a similar model were studied in simulations using fluctuation expressions 32 .…”

Section: Introductionmentioning

confidence: 99%

Dipolar interactions, molecular flexibility, and flexoelectricity in bent-core liquid crystals

Dewar

Camp

2005

The Journal of Chemical Physics

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The effects of dipolar interactions and molecular flexibility on the structure and phase behavior of bent-core molecular fluids are studied using Monte Carlo computer simulations. Some calculations of flexoelectric coefficients are also reported. The rigid cores of the model molecules consist of either five or seven soft spheres arranged in a 'V' shape with external bend angle γ. With purely repulsive sphere-sphere interactions and γ = 0 • (linear molecules) the seven-sphere model exhibits isotropic, uniaxial nematic, smectic-A, and tilted phases. With γ ≥ 20 • the smectic-A phase disappears, while the system with γ ≥ 40 • shows a direct tilted smectic-isotropic fluid transition. The addition of electrostatic interactions between transverse dipole moments on the apical spheres is generally seen to reduce the degree of tilt in the smectic and solid phases, destabilize the nematic and smectic-A phases of linear molecules, and destabilize the tilted smectic-B phase of bent-core molecules. The effects of adding three-segment flexible tails to the ends of five-sphere bent-core molecules are examined using configurational-bias Monte Carlo simulations. Only isotropic and smectic phases are observed. On the one hand, molecular flexibility gives rise to pronounced fluctuations in the smectic-layer structure, bringing the simulated system in better correspondence with real materials; on the other hand, the smectic phase shows almost no tilt. Lastly, the flexoelectric coefficients of various nematic phases -with and without attractive sphere-sphere interactions -are presented. The results are encouraging, but the computational effort required is a drawback associated with the use of fluctuation relations.

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“…36 There have only been three simulation studies of the flexoelectric effect. [37][38][39][40] Two of these used simple models of wedge-shaped liquid crystal molecules formed by fusing a Gay-Berne molecule and a Lennard-Jones molecule. The first of these studies 37,38 used a density functional approach based on Ref.…”

Section: Introductionmentioning

confidence: 99%

“…[37][38][39][40] Two of these used simple models of wedge-shaped liquid crystal molecules formed by fusing a Gay-Berne molecule and a Lennard-Jones molecule. The first of these studies 37,38 used a density functional approach based on Ref. 29 while the second used a linear-response formalism.…”

Section: Introductionmentioning

confidence: 99%

Calculation of flexoelectric coefficients for a nematic liquid crystal by atomistic simulation

Cheung

Clark

Wilson

2004

The Journal of Chemical Physics

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Flexoelectric effects in liquid crystals formed by pear-shaped molecules. A computer simulation study

Cited by 27 publications

References 32 publications

Computer simulations of hard pear-shaped particles

Computer simulations of hard pear-shaped particles

Dipolar interactions, molecular flexibility, and flexoelectricity in bent-core liquid crystals

Calculation of flexoelectric coefficients for a nematic liquid crystal by atomistic simulation

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