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Updated: Jan 31, 2026
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High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
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Non-monotonic, lily-like twist distribution in toroidal nematics
Andrea Pedrini1, Marco Piastra2, Epifanio G Virga3
1Dipartimento di Matematica, Università di Pavia, via Ferrata 5, 27100 Pavia, Italy. andrea.pedrini@unipv.it.
Soft Matter
|January 5, 2019
Summary
Toroidal nematics exhibit a stable, non-monotonic twist distribution, resembling a lily-like surface, not a simple fennel shape. This finding challenges previous assumptions about their equilibrium states.
Area of Science:
- Physics
- Materials Science
- Soft Matter Physics
Background:
- Toroidal nematics are liquid crystal droplets with a torus shape.
- Planar degenerate boundary conditions allow for a bend-only director field equilibrium.
- Instabilities arise in the twist elastic constant for small values.
Purpose of the Study:
- Investigate the global equilibrium twist distribution in toroidal nematics.
- Determine if the twist distribution is monotonic or non-monotonic under specific conditions.
- Explore the complex elastic free-energy functional in a non-linear setting.
Main Methods:
- Analytical proof of twist distribution.
- Development of a deep-learning optimization method for complex functionals.
- Validation and documentation of the deep-learning approach.
Main Results:
- The stable twist distribution is non-monotonic, forming a 'lily-like' surface.
- The maximum twist can occur within the torus, not just at the boundary.
- A novel deep-learning method was successfully applied and validated.
Conclusions:
- The equilibrium twist in toroidal nematics is generically non-monotonic.
- Deep-learning methods offer a viable solution for analytically intractable problems in soft matter physics.
- The study provides new insights into the behavior of toroidal liquid crystals.
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