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Topological defects of dipole patchy particles on a spherical surface.
Uyen Tu Lieu1, Natsuhiko Yoshinaga2
1Mathematics for Advanced Materials-OIL, AIST, 2-1-1 Katahira, Aoba, 980-8577 Sendai, Japan. uyen.lieu@aist.go.jp.
Soft Matter
|August 18, 2020
Summary
Dipole-like particles form ordered square lattices on spheres. Topological constraints cause defects, with four +1/2 defects and eight grain boundary scars appearing predictably with sphere size.
Area of Science:
- Soft Matter Physics
- Statistical Mechanics
- Computational Materials Science
Background:
- Understanding particle self-assembly is crucial for materials science.
- Topological defects arise in confined systems due to geometric constraints.
- Spherical confinement introduces unique challenges for ordered structures.
Purpose of the Study:
- To investigate the assembly of dipole-like patchy particles on a spherical surface.
- To analyze the nature and behavior of topological defects in this system.
- To understand the relationship between defects and positional order.
Main Methods:
- Brownian dynamics simulations were employed.
- Particles were confined to a spherical surface.
- Surface properties were described using spherical harmonic Y10.
- Particle orientation was defined by a uniaxial axis.
Main Results:
- A defect-free square lattice with nematic order was observed in flat space.
- On a spherical surface, four +1/2 defects were found, satisfying the Euler characteristic.
- Defect configurations were often found near a great circle.
- Eight grain boundary scars proliferated linearly with sphere size.
- Scars' positions and orientations correlated with defect cores.
Conclusions:
- Spherical confinement leads to predictable defect formation in particle assemblies.
- The number and behavior of defects are governed by topological constraints.
- Grain boundary scars are linked to defect cores and scale with system size.
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