Phase and vacancy behaviour of hard "slanted" cubes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Understanding the phase behavior of non-spherical particles is crucial for designing novel materials.
• Hard rhombic prisms represent a geometrically intriguing model system for studying crystallization phenomena.

Purpose of the Study:

• To investigate the equilibrium phase behavior of hard, right rhombic prisms.
• To characterize the crystal structures formed as a function of particle shape (slant angle) and density.

Main Methods:

• Event-driven molecular dynamics simulations
• Monte Carlo simulations
• Free-energy calculations

Main Results:

• A simple cubic crystal structure is the equilibrium phase for a broad range of slant angles and densities, despite the particles' non-cubic symmetry.
• The equilibrium vacancy concentration in the simple cubic phase is remarkably high and depends solely on packing fraction, not particle shape.
• At higher densities, a rhombic crystal emerges as the equilibrium phase.

Conclusions:

• The phase behavior of hard rhombic prisms is complex and can lead to unexpected crystal structures.
• The findings provide insights into the role of particle shape and packing in determining equilibrium phases and defect concentrations.