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Topological defects are one of the most conspicuous features of liquid crystals. In two dimensional nematics, they have been shown to behave effectively as particles with both, charge and orientation, which dictate their interactions. Here,…

Soft Condensed Matter · Physics 2021-07-14 Daniel J. G. Pearce , Karsten Kruse

We use lattice Boltzmann simulations of the Beris--Edwards formulation of nematodynamics to probe the response of a nematic liquid crystal with conflicting anchoring at the boundaries under shear and Poiseuille flow. The geometry we focus…

Soft Condensed Matter · Physics 2009-11-10 D. Marenduzzo , E. Orlandini , J. M. Yeomans

We present a theoretical study of the director fields and energetics of nematic liquid crystal shells with two pairs of surface defects. The pairs of defects can undergo abrupt transitions between a configuration of maximum separation to at…

Soft Condensed Matter · Physics 2012-11-21 V. Koning , T. Lopez-Leon , A. Fernandez-Nieves , V. Vitelli

We consider a phenomenological continuum theory for an extensile, overdamped active nematic liquid crystal, applicable in the dense regime. Constructed from general principles, the theory is universal, with parameters independent of any…

Soft Condensed Matter · Physics 2015-06-12 Elias Putzig , Gabriel S. Redner , Arvind Baskaran , Aparna Baskaran

A nematic liquid crystal confined to the surface of a sphere exhibits topological defects of total charge $+2$ due to the topological constraint. In equilibrium, the nematic field forms four $+1/2$ defects, located at the corners of a…

Soft Condensed Matter · Physics 2020-07-22 Yi-Heng Zhang , Markus Deserno , Zhan-Chun Tu

Liquid crystals generally support orientational singularities of the director field known as topological defects. These latter modifiy transport properties in their vicinity as if the geometry was non-Euclidean. We present a state of the…

Soft Condensed Matter · Physics 2023-07-06 Sébastien Fumeron , Bertrand Berche , Fernando Moraes

Aqueous dispersions of exfoliated, bile-salt stabilized single-wall carbon nanotubes exhibit a first order transition to a nematic liquid-crystalline phase. The nematic phase presents itself in the form of micron-sized nematic droplets also…

Soft Condensed Matter · Physics 2013-06-25 Nicolas Puech , Eric Grelet , Philippe Poulin , Christophe Blanc , Paul van der Schoot

Defects in liquid crystals are of great practical importance and theoretical interest. Despite tremendous efforts, predicting the location and transition of defects under various topological constraint and external field remains to be a…

Soft Condensed Matter · Physics 2014-08-27 Yucheng Hu , Yang Qu , Pingwen Zhang

Substrates which are chemically or topographically patterned induce a variety of liquid crystal textures. The response of the liquid crystal to competing surface orientations, typical of patterned substrates, is determined by the anisotropy…

Soft Condensed Matter · Physics 2016-12-21 Nuno M. Silvestre , Jose M. Romero-Enrique , Margarida M. Telo da Gama

A nematic membrane is a sheet with embedded orientational order, which can occur in biological cells, liquid crystal films, manufactured materials, and other soft matter systems. By formulating the free energy of nematic films using tensor…

Soft Condensed Matter · Physics 2009-11-13 John R. Frank , Mehran Kardar

The structure of a molecular liquid, in both the nematic liquid crystalline and isotropic phases, around a cylindrical macroparticle, is studied using density functional theory. In the nematic phase the structure of the fluid is highly…

Soft Condensed Matter · Physics 2009-11-11 David L. Cheung , Michael P. Allen

Topological defects in systems with liquid-crystalline order are crucial in determining their large-scale properties. In active systems, they are known to have properties impossible at equilibrium: for example, $+1/2$ defects in…

Soft Condensed Matter · Physics 2026-02-17 Giacomo Marco La Montagna , Sumeja Burekovic , Ananyo Maitra , Cesare Nardini

The motion of topological defects is an important feature of the dynamics of all liquid crystals, and is especially conspicuous in active liquid crystals. Understanding defect motion is a challenging theoretical problem, because the…

Soft Condensed Matter · Physics 2019-01-24 Xingzhou Tang , Jonathan V. Selinger

Liquid crystals in two dimensions undergo a first-order isotropic-to-quasi-nematic transition, provided the particle interactions are sufficiently ``sharp and narrow''. This implies phase coexistence between isotropic and quasi-nematic…

Statistical Mechanics · Physics 2009-11-13 R. L. C. Vink

In culture migrating and interacting amoeboid cells can form nematic liquid crystal phases. A polar nematic liquid crystal is formed if the interaction has a polar symmetry. One type of white blood cells (granulocytes) form clusters where…

Biological Physics · Physics 2007-05-23 Ralf Kemkemer , Dieter Kling , Dieter Kaufmann , Hans Gruler

Topological defects are an essential part of the structure and dynamics of all liquid crystals, and they are particularly important in experiments and simulations on active liquid crystals. In a recent paper, Vromans and Giomi [Soft Matter,…

Soft Condensed Matter · Physics 2017-08-23 Xingzhou Tang , Jonathan V. Selinger

A Self Consistent Field Theory description of equilibrium, but non uniform, configurations adopted by semi flexible liquid crystal molecules is presented. Two cases are considered, isotropic-nematic phase boundaries, and topological defects…

Soft Condensed Matter · Physics 2025-03-03 Longyu Qing , Jorge Viñals

From the theory of topological defect formation proposed for the early universe, the so called Kibble mechanism, it follows that the density correlation functions of defects and anti-defects in a given system should be completely determined…

High Energy Physics - Phenomenology · Physics 2009-11-07 Rajarshi Ray , Ajit M. Srivastava

In soft matter, the phase of nematic liquid crystals can be made from anisotropic molecules in single component materials, or as a suspension of mesoscopic nematogens. The later offers more versatility in the experimental design of complex…

Soft Condensed Matter · Physics 2025-10-23 Mathieu Dedenon

Defects arise when nematic liquid crystals are under topological constraints at the boundary. Recently the study of defects has drawn a lot of attention. In this paper, we investigate the relationship between two-dimensional defects and…

Soft Condensed Matter · Physics 2015-10-16 Yang Qu , Ying Wei , Pingwen Zhang