Simulation of cholesteric blue phases using a Landau-de Gennes theory: Effect of an applied electric field

Junichi Fukuda, Makoto Yoneya, Hiroshi Yokoyama

研究成果: Contribution to journalArticle査読

55 被引用数 (Scopus)

抄録

We investigate numerically static and dynamic properties of cholesteric blue phases. Our study is based on a Landau-de Gennes theory describing the orientational order of a liquid crystal in terms of a second-rank tensor. To find the shape and size of the unit cell conforming to the minimum of the free energy, we let the geometrical parameters characterizing the unit cell relax in the course of the time evolution via a simple relaxational equation. We investigate the effect of an electric field on the structure of cholesteric blue phases. We study how the deformation of the unit cell in response to the electric field E depends on the strength and direction of the electric field and the original structure of cholesteric blue phases. Our results qualitatively agree with the experimental findings. Although in a weak field, the strain tensor is proportional to E2 as previously argued, for a moderate field the distortion is no longer proportional to E2 and can be even nonmonotonic with respect to E2. Furthermore, we investigate the kinetic processes of the deformation, rearrangement, and extinction of disclination lines under a strong electric field. We show that the kinetics of disclination lines is highly complicated and sensitively depends on the initial structure of blue phases, the direction of the electric field, and the sign of dielectric anisotropy Ia. In most cases, a strong field aligns the liquid crystals in a uniform (positive Ia) or helical (negative Ia) manner without disclination lines. However, for negative Ia and the direction of the electric field parallel to the body diagonal of the unit cell, disclination lines do not disappear and form a two-dimensional hexagonal lattice.

本文言語英語
論文番号031706
ジャーナルPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
80
3
DOI
出版ステータス出版済み - 9 15 2009
外部発表はい

All Science Journal Classification (ASJC) codes

  • 統計物理学および非線形物理学
  • 統計学および確率
  • 凝縮系物理学

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