On Defects in Biaxial Nematic Films with Random Planar Surface Alignment: A Monte Carlo Study

Preeti, G. Sai; Chiccoli, C.; Pasini, Paolo; Sastry, V. S. S.; Zannoni, Claudio

doi:10.1080/15421406.2012.763214

Cited by 5 publications

(2 citation statements)

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“…To examine effects of finite temperature and continuous twist rate, we simulate a nematic liquid crystal in a cell with the same geometry as Fig. 2, using a modified Lebwohl-Lasher rotor model [30][31][32]. The liquid crystal is represented as a uniaxial nematic with a unit director field ni defined on each site i of a cubic lattice, interacting through the nearest-…”

Section: Simulations: Finite Twist Ratementioning

confidence: 99%

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Frank-Read Mechanism in Nematic Liquid Crystals

Cheng

Deutsch

Angelo

et al. 2023

Preprint

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In a crystalline solid under mechanical stress, a Frank-Read source is a pinned dislocation segment that repeatedly bows and detaches, generating concentric dislocation loops. We demonstrate that in nematic liquid crystals, an analogous Frank-Read mechanism generates concentric disclination loops. Using experiment, simulation, and theory, we study a disclination segment pinned between surface defects on one substrate in a nematic cell. Under applied twist of the nematic director, the pinned segment bows and emits a new disclination loop which expands, leaving the original segment intact; loop emission repeats for each additional 180 degrees of applied twist. We present experimental micrographs showing loop expansion and snap-off, numerical simulations of loop emission under both quasistatic and dynamic loading, and theoretical analysis considering both free energy minimization and the balance of competing forces. Lastly, we discuss potential use of Frank-Read sources to modify microstructural evolution in both passive and active nematics.

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Section: Simulations: Finite Twist Ratementioning

confidence: 99%

“…The Lebwohl-Lasher potential effectively brings neighboring spins into parallel alignment and accurately reproduces disclination behavior of liquid crystal systems [30,31,43]. Spins can be fixed at the boundary and patterned to represent a strongly anchored layer.…”

Section: Simulations Of Lattice Modelmentioning

confidence: 99%