Molecular field theory of nematics: density functional approach. I. Bulk effects

Sluckin, T. J.; Shukla, Prabodh

doi:10.1088/0305-4470/16/7/030

Cited by 85 publications

(30 citation statements)

References 26 publications

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“…A molecular theory of elasticity of nematic LCs can be developed using the density functional approach to the theory of nematic LCs (see, for example, [27][28][29]) and employing the gradient expansion of the orientational distribution function [30][31][32] (see also [33][34][35] and references therein on the earlier works). In this approach, the free energy of a liquid crystal, F , is a functional of the orientational distribution function f .…”

Section: Molecular Theory Of Elasticity Of Nematics Without Polar Ordermentioning

confidence: 99%

Effect of polar intermolecular interactions on the elastic constants of bent-core nematics and the origin of the twist-bend phase

Osipov

Paja̧k

2016

Eur. Phys. J. E

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Abstract. A molecular theory of both elastic constants and the flexoelectric coefficients of bent-core nematic liquid crystals has been developed taking into account dipole-dipole interactions as well as polar interactions determined by the bent molecular shape. It has been shown that if polar interactions are neglected, the elastic constants are increasing monotonically with the decreasing temperature. On the other hand, dipolar interactions between bent-core molecules may result in a dramatic increase of the bend flexocoefficient. As a result, the flexoelectric contribution to the bend elastic constant increases significantly, and the bend elastic constant appears to be very small throughout the nematic range and may vanish at a certain temperature. This temperature may then be identified as a temperature of the elastic instability of the bent-core nematic phase which induces a transition into the modulated phases with bend deformations like recently reported twist-bend phase. The temperature variation of the elastic constants is qualitatively similar to the typical experimental data for bent-core nematics.

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Section: Molecular Theory Of Elasticity Of Nematics Without Polar Ordermentioning

confidence: 99%

Effect of polar intermolecular interactions on the elastic constants of bent-core nematics and the origin of the twist-bend phase

Osipov

Paja̧k

2016

Eur. Phys. J. E

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“…of the uniform liquid of density p R . A considerable number of papers applying DFT to liquid crystals use equation (145) as a starting point (Workman and Fixman 1973, Sluckin and Shukla 1983, Upkin and Oxtoby 1983, Singh 1984, Kloczkowski and Stecki 1985, Singh and Singh 1986, Marko 1988, Singh et al 1989. Because c< 3 ) is not known except for a uniform liquid of hard spherical particles (Rosenfeld et al 1990) the Taylor series is usually truncated after the quadratic term.…”

Section: Expansion Around a Uniform Liquidmentioning

confidence: 99%

Phase transitions in lyotropic colloidal and polymer liquid crystals

1992

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An overview is given of theory and experiments on liquid crystal phases which appear in solutions of elongated colloidal particles or stiff polymers. The Onsager (1949) virial theory for the isotropic-nematic transition of thin rodlike particles is treated comprehensively along with extensions to polydisperse solutions and soft interactions. Computer simulations of liquid crystal phases in hard particle fluids are summarized and used to assess the quality of statistical mechanical theories for stiff particles at higher volume fraction-like the inclusion of higher virial coefficients, y-expansion, scaled particle theory and density functional theory. Both computer simulations and density functional theory indicate formation of more highly ordered smectic phases. The range of experimental applicability is strongly widened by the extension of the virial theory to wormlike chains by Khokhlov andSemenov (1981, 1982). Finally, experimental results for a number of carefully studied, charged and uncharged colloids and polymers are summarized and compared to theoretical results. In many cases the agreement is semi-quantitative.

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“…Equation (2) may thus be expected to be qualitatively incorrect for small values of q2. This need not be a serious flaw, however, for typically one wants C(12) as an integrand where it will first be multiplied by a power of r12 [15,16], a step which would in any case wash out most of the short-range structure of a more correct C (12).…”

Section: Introductionmentioning

confidence: 99%