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Phase behavior of colloidal superballs: shape interpolation from spheres to cubes
Robert D Batten1, Frank H Stillinger, Salvatore Torquato
1Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 28, 2010
Summary
The phase behavior of hard superballs, which are convex particles with tunable shapes, was studied. Asphericity significantly impacts their liquid and crystal phases, revealing transitions from ordered crystals to less ordered states with decreasing density.
Area of Science:
- Materials Science
- Computational Physics
- Chemical Engineering
Background:
- Understanding particle phase behavior is crucial for materials design.
- Superballs offer a tunable model system bridging spheres and cubes.
- Previous studies lacked detailed analysis of superball phase transitions and ordering.
Purpose of the Study:
- To investigate the phase behavior of hard superballs with varying asphericity.
- To analyze the impact of particle shape on liquid and crystal ordering.
- To explore phase transitions under density changes and identify potential artifacts in simulations.
Main Methods:
- Molecular dynamics simulations using deformable periodic boxes.
- Systematic variation of the superball deformation parameter (q).
- Analysis of virial coefficients, order parameters, and correlation functions.
Main Results:
- Asphericity significantly influences cubatic ordering in liquid and crystal phases.
- Low-density equations of state can resemble spheres even for cube-like superballs.
- Superballs exhibit density-driven phase transitions from ordered crystals to less ordered states for 1
Conclusions:
- Superball asphericity is key to cubatic order, with distinct behaviors for different q ranges.
- Long-ranged orientational order persists until melting for q≥3.
- Deformable simulation boxes are essential to avoid artificial phase transitions, enabling experimental investigation of colloidal superballs.
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