Scaled Chiral Indices for Ferroelectric Liquid Crystals

Solymosi, Miklos; Low, Robert J.; Grayson, Martin; Neal, Maureen P.; Wilson, Mark R.; Earl, David J.

doi:10.1080/00150190214456

Cited by 17 publications

(17 citation statements)

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“…Sampling of was carried out at intervals of 200 MC steps with a new molecular surface generated for each sample. For each molecule and each temperature studied, runs in excess of 2ϫ10 6 MC steps were carried out. Checks for convergence of the mean steric energy, values, and of dihedral angle distributions were carried out in each case.…”

Section: Methodsmentioning

confidence: 99%

“…As a comparison in Fig. 2 we show also predicted values of ␤ M determined using the scaled chiral index 6,7,29 that is calculated from…”

Section: Rigid Chiral Moleculesmentioning

confidence: 99%

“…An actual quantitative measure of the magnitude of chirality for a given molecular conformation and a link to pseudoscalar properties such as the HTP or circular dichroism, has been more difficult to obtain. However, recent success has been found through calculations of the difference in chemical potential for enantiomers in a twisted nematic host, 4,5 in calculations of a scaled chiral index, 6,7 using a mean field approximation that takes into account chiral dispersive interactions 8 and with the chirality order parameter approach of Nordio, Ferrarini, and co-workers. [9][10][11][12][13][14][15][16] In order to determine a relationship between the molecular shape and a pseudoscalar property such as the HTP, these studies have, by necessity, been limited to relatively rigid chiral dopants where the molecular conformation is unlikely to vary significantly from the minimum energy structure that can be found from x-ray diffraction experiment and by theoretical techniques such as molecular mechanics and density functional theory.…”

Section: Introductionmentioning

confidence: 99%

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Predictions of molecular chirality and helical twisting powers: A theoretical study

Earl

Wilson

2003

The Journal of Chemical Physics

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A theoretical study of a number of chiral molecules has been undertaken using a molecular Monte Carlo simulation approach coupled with calculations of molecular chirality based on a chirality order parameter. Results for a variety of TADDOL (α,α,α′,α′-tetraaryl-1,3-dioxolan-4,5dimethanol) derivatives show good agreement with experimental findings for the sign, magnitude, and the temperature dependence of the helical twisting power (HTP). For a photochromic chiral dopant with variable HTP we are able to model the reduction in the HTP when photoisomerization occurs. Our studies on a liquid crystalline material with a single chiral center have reproduced a temperature dependent twist inversion in the material. We discuss the temperature and solvent dependence of the helical twisting power and argue that in all the systems studied here, preferential selection of certain molecular conformations at different temperatures and in different solvents are able to explain the observed experimental behavior of the HTP.

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Section: Methodsmentioning

confidence: 99%

“…As a comparison in Fig. 2 we show also predicted values of ␤ M determined using the scaled chiral index 6,7,29 that is calculated from…”

Section: Rigid Chiral Moleculesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Predictions of molecular chirality and helical twisting powers: A theoretical study

Earl

Wilson

2003

The Journal of Chemical Physics

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“…In addition to the chirality order parameter, there are other methods of studying HTPs. Recent success has been achieved with a scaled chiral index [120,121] and a mean field approximation that takes into account chiral dispersive interactions [122]. In the case of the former, no account is taken of the surrounding fluid.…”

Section: Helical Twisting Powersmentioning

confidence: 99%

Progress in computer simulations of liquid crystals

Wilson

2005

International Reviews in Physical Chemistry

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137

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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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“…They are even in the sense that if O is a shape and O ′ is its mirror image, then χ(O) = χ(O ′ ). Other indices, such as the scaled chiral index G 0S , 4,5,6,7,8,9 based on the Osipov chirality index G 0 , 10 and the chirality order parameter Q of Nordio and co-workers 11,12,13 are particularly designed to quantify the relationship between the chirality of molecules and measurable pseudoscalar properties such as helical twisting power (HTP).…”

Section: Introductionmentioning

confidence: 99%