Theory and simulation of the nematic zenithal anchoring coefficient

Andrienko, Denis; Allen, Michael

doi:10.1103/physreve.65.021704

Cited by 28 publications

(38 citation statements)

References 27 publications

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“…Their evaluation from director fluctuations has been particularly popular [39][40][41][42] , while relationships between elastic constants and orientation-dependent pair-correlation functions known from density functional theory [43][44][45] have been also utilised 41,46,47 . Their evaluation from director fluctuations has been particularly popular [39][40][41][42] , while relationships between elastic constants and orientation-dependent pair-correlation functions known from density functional theory [43][44][45] have been also utilised 41,46,47 .…”

Section: Introductionmentioning

confidence: 99%

Fluctuation spectra in polymer nematics and Frank elastic constants: a coarse-grained modelling study

Gemünden

Daoulas

2015

Soft Matter

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Monte Carlo simulations of uniaxial nematic polymer melts are performed, based on a discrete worm-like chain model combined with soft, anisotropic non-bonded potentials. Different chain lengths are considered, the contour length of the longest being an order of magnitude larger than the persistence length. From equilibrated melt configurations, density and director fluctuation spectra are calculated and compared with analytical predictions available in literature. The latter typically correspond to hydrodynamic treatments of correlations and assume that there is no chain backfolding along the nematic director. Nevertheless, it is demonstrated that the analytical theories capture several features of the spectra obtained in the current simulations, where moderate backfolding of polymer chains is observed. Based on the available analytical expressions for density and director fluctuation spectra, material properties, such as Frank elastic constants, are extracted. Their dependence on polymerisation degree is studied and found to reproduce theoretically expected trends. For example, evidence is provided that the splay constant increases linearly with chain length, when effects of hairpins are negligible.

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Section: Introductionmentioning

confidence: 99%

Fluctuation spectra in polymer nematics and Frank elastic constants: a coarse-grained modelling study

Gemünden

Daoulas

2015

Soft Matter

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“…Experimental studies have been performed using methods such as scanning tunnelling microscopy, 2 atom force microscopy, 3 and NMR, 4 among others. There have also been simulation studies, using lattice models, 5 hard 6,7 or soft single site models, 8 and a few studies using atomistic models. 9 It has also been studied by the all commonly used theoretical methods in liquid-crystal science.…”

Section: Introductionmentioning

confidence: 99%

“…However, the former makes some assumptions ͑e.g., slow director variation͒ that are invalid near a solid substrate, while the latter introduces phenomenological parameters that are not easily related to microscopic properties. Last, there have been several studies using density-functional theory ͑DFT͒, 6,7,[11][12][13] or integral equation methods. 14,15 In this paper we study a liquid-crystal fluid near a solid substrate using DFT.…”

Section: Introductionmentioning

confidence: 99%

A density-functional theory study of the confined soft ellipsoid fluid

Cheung

Schmid

2004

The Journal of Chemical Physics

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A system of soft ellipsoid molecules confined between two planar walls is studied using classical density-functional theory. Both the isotropic and nematic phases are considered. The excess free energy is evaluated using two different Ansätze and the intermolecular interaction is incorporated using two different direct correlation functions ͑DCF's͒. The first is a numerical DCF obtained from simulations of bulk soft ellipsoid fluids and the second is taken from the Parsons-Lee theory. In both the isotropic and nematic phases the numerical DCF gives density and order parameter profiles in reasonable agreement with simulation. The Parsons-Lee DCF also gives reasonable agreement in the isotropic phase but poor agreement in the nematic phase.

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“…This makes it possible to model very large numbers of individual molecules and is particularly useful for studying interfacial phenomena. Consequently, there has been considerable work on studying the properties of liquid crystals in contact with solid surfaces [54][55][56][57] and looking at a nematic-isotropic interface [58][59][60][61]. The former is of particular practical importance because surface-induced planar or homotropic ordering is used in most liquid crystal displays.…”

Section: Simulation Models For Liquid Crystal Phasesmentioning

confidence: 99%

Progress in computer simulations of liquid crystals

Wilson

2005

International Reviews in Physical Chemistry

139

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This article reviews some of the recent progress in the simulation of liquid crystals across a range of length and time scales. Simulators now have an extensive range of models at their disposal, ranging from fully atomistic studies where each atom is represented in a simulation, via hard or soft anisotropic potentials, to lattice models and director-based simulation methods. Each of these provide access to different phenomena. The progress towards accurate atomistic modelling of nematics is discussed in detail, pointing to improvements in force fields made recently and discussing the progress towards accurate prediction of material properties. Three material properties are discussed in detail: elastic constants, rotational viscosity and helical twisting powers. The simulation methods that can be employed to extract such properties are reviewed and the insights provided by recent results from atomistic and coarse-grained models are discussed. The article points also to the recent success of coarse-grained modelling in helping to understand the structure of complex macromolecular liquid crystals: liquid crystal polymers and liquid crystal dendrimers in which the macromolecules contain different types of interaction site. Finally, it is worth noting that throughout Nature liquid crystals occur as the archetypal self-assembled materials; able to form well-defined self-organized structures, which are often ordered at the nanoscale. With this in mind, some perspectives on the future use of these materials are presented, with suggestions for how liquid crystal simulation can be used to help in the design of the next generation of nanoscale devices.

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Theory and simulation of the nematic zenithal anchoring coefficient

Abstract: Combining molecular simulation, Onsager theory and the elastic description of nematic liquid crystals, we study the dependence of the nematic liquid crystal elastic constants and the zenithal surface anchoring coefficient on the value of the bulk order parameter.

Cited by 28 publications

References 27 publications

Fluctuation spectra in polymer nematics and Frank elastic constants: a coarse-grained modelling study

Fluctuation spectra in polymer nematics and Frank elastic constants: a coarse-grained modelling study

A density-functional theory study of the confined soft ellipsoid fluid

Progress in computer simulations of liquid crystals

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