Defect Core Structure in Nematic Liquid Crystals

Schopohl, N.; Sluckin, T. J.

doi:10.1103/physrevlett.59.2582

Cited by 322 publications

(270 citation statements)

References 7 publications

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“…A more quantitative description of the free energy of a disclination has to start from the Landau-Ginzburgde Gennes free energy with the full alignment tensor Q [32,33]. We finish this subsection with an important remark about length scales.…”

Section: A Geometrymentioning

confidence: 99%

Director field configurations around a spherical particle in a nematic liquid crystal

1999

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We study the director field around a spherical particle immersed in a uniformly aligned nematic liquid crystal and assume that the molecules prefer a homeotropic orientation at the surface of the particle. Three structures are possible: a dipole, a Saturn-ring, and a surface-ring configuration, which we investigate by numerically minimizing the Frank free energy supplemented by a magneticfield and a surface term. In the dipole configuration, which is the absolutely stable structure for micron-size particles and sufficiently strong surface anchoring, a twist transition is found and analyzed. We show that a transition from the dipole to the Saturn ring configuration is induced by either decreasing the particle size or by applying a magnetic field. The effect of metastability and the occurence of hysteresis in connection with a magnetic field are discussed. The surface-ring configuration appears when the surface-anchoring strength W is reduced. It is also favored by a large saddle-splay constant K24. A comparison with recent experiments [10,13] gives a lower bound for W, i.e., W > 0.6 erg/cm 2 for the interface of water and pentylcyanobiphenyl (5CB) in the presence of the surfactant sodium dodecyl sulfate.

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Section: A Geometrymentioning

confidence: 99%

Director field configurations around a spherical particle in a nematic liquid crystal

1999

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“…If the vari ation from one grid point to its neighbors is small, one has nv(/1? i2, i3) nv(i{ ± 1, i2, t3) % 1, and DT ß reduces to On the other hand, for directors which enclose angles > 90 at adjacent grid points, the difference between (18) and (19) is really crucial. In particular, antiparallel neighbors are treated like parallel ones according to (18), but not to (19).…”

Section: Spatial Discretizationmentioning

confidence: 99%

“…The superscripts "T" and "V" in (18) and (19) refer to "tensorial" and "vectorial" since (18) preserves the tensorial symmetry. If the vari ation from one grid point to its neighbors is small, one has nv(/1?…”

Section: Spatial Discretizationmentioning

confidence: 99%

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Derivation and Application of an Algorithm for the Numerical Calculation of the Local Orientation of Nematic Liquid Crystals

Kilian

Hess

1989

Zeitschrift Für Naturforschung A

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D e r iv a tio n a n d A p p lic a tio n o f a n A lg o rith m fo r th e N u m e ric a l C a lc u la tio n o f th e L o c a l O r ie n ta tio n o f N e m a tic L iq u id C r y s ta ls A. Kilian and S. Hess Institut für Theoretische Physik, Technische Universität Berlin, Berlin Z. Naturforsch. 44 a, 693 -703 (1989); received June 16, 1989 Starting from a relaxation equation for the alignment tensor, an algorithm is derived which allows the numerical calculation of the dynamic and static behavior of the director field n with the correct nematic symmetry property, where n and -n are equivalent. As a first application, a two-dimensio nal problem is treated where the typical nematic defects with half-integer winding numbers only occur when the algorithm with the correct nematic symmetry property is used. Furthermore, the method is applied to the static and dynamic behavior of a Frederiks cell with strong and weak anchoring.

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“…4 Eigenvalue exchange (also called order reconstruction) was first proposed by Schopohl and Sluckin within the defect core of M = ±1/2 wedge disclinations. 5 Since then, several theoretical [6][7][8][9][10][11] and experimental [12][13][14][15] studies have analyzed the detailed core structure in NLC under various boundary conditions. In particular, Palffy-Muhoray 6 investigated the eigenvalue exchange problem in a hybrid alignment nematic (HAN) cell with a perpendicular alignment of NLC molecules on one surface and a parallel alignment on the other.…”

Section: Introductionmentioning

confidence: 99%

New surface order reconstruction induced by electric field application in a nanoconfined HAN cell with a topological defect

Wang

Zhou

et al. 2015

AIP Advances

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In accordance with the 2D Landau–de Gennes tensorial formalism, we investigated the influence of an applied electric field E parallel to the defect line on the position and structure of a nematic line defect with topological charge M = − 1/2 in a hybrid alignment nematic cell with different cell gaps d. A new type of surface order reconstruction occurs in the cell as E is increased. Regardless of d, two biaxial layers can be achieved near the top and bottom substrates of the cell with different E values. This process involves double eigenvalue exchange across the cell. However, the structural transition processes vary for different d values.

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Defect Core Structure in Nematic Liquid Crystals

Cited by 322 publications

References 7 publications

Director field configurations around a spherical particle in a nematic liquid crystal

Director field configurations around a spherical particle in a nematic liquid crystal

Derivation and Application of an Algorithm for the Numerical Calculation of the Local Orientation of Nematic Liquid Crystals

New surface order reconstruction induced by electric field application in a nanoconfined HAN cell with a topological defect

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