Morse Theory and Meron Mediated Interactions Between Disclination Lines in Nematics

Fuente: arXiv
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Autori principali: Pollard, Joseph, Morris, Richard G.
Natura: Preprint
Pubblicazione: 2024
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author Pollard, Joseph
Morris, Richard G.
author_facet Pollard, Joseph
Morris, Richard G.
contents The topological understanding of nematic liquid crystals is traditionally centered on singularities, or defects, and their classification via homotopy theory. However, this approach has ultimately proved insufficient to properly capture a range of complex behaviours that have been reported in three dimensions. To address this, we argue that a finer understanding of topology is required, in which non-singular but non-trivial topological solitons - so-called merons - play a central role in mediating interactions between disclination lines. We present a comprehensive framework for capturing such behaviour that draws heavily on aspects of Morse theory; the key notion being that merons appear singular under projection onto a two-dimensional surface. This permits the use of singularity theory and dividing curves to characterise nematic textures via tomography, as well as an understanding of topological transitions via surgery theory. We use our ideas to understand and classify complex three-dimensional behaviours, such as the linking, rewiring and crossing of disclination lines, as well as to provide a new perspective on defect charge.
format Preprint
id arxiv_https___arxiv_org_abs_2408_01032
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Morse Theory and Meron Mediated Interactions Between Disclination Lines in Nematics
Pollard, Joseph
Morris, Richard G.
Soft Condensed Matter
Mathematical Physics
The topological understanding of nematic liquid crystals is traditionally centered on singularities, or defects, and their classification via homotopy theory. However, this approach has ultimately proved insufficient to properly capture a range of complex behaviours that have been reported in three dimensions. To address this, we argue that a finer understanding of topology is required, in which non-singular but non-trivial topological solitons - so-called merons - play a central role in mediating interactions between disclination lines. We present a comprehensive framework for capturing such behaviour that draws heavily on aspects of Morse theory; the key notion being that merons appear singular under projection onto a two-dimensional surface. This permits the use of singularity theory and dividing curves to characterise nematic textures via tomography, as well as an understanding of topological transitions via surgery theory. We use our ideas to understand and classify complex three-dimensional behaviours, such as the linking, rewiring and crossing of disclination lines, as well as to provide a new perspective on defect charge.
title Morse Theory and Meron Mediated Interactions Between Disclination Lines in Nematics
topic Soft Condensed Matter
Mathematical Physics
url https://arxiv.org/abs/2408.01032