Pattern formation in two-dimensional hard-core/soft-shell systems with variable soft shell profiles

Area of Science:

• Materials Science
• Soft Matter Physics
• Computational Chemistry

Background:

• Hard-core/soft shell (HCSS) particles self-assemble into complex structures under compression.
• Existing models often use unrealistic square shoulder potentials for soft shell interactions, lacking repulsion.
• Experimental HCSS systems exhibit repulsive forces within the soft shell regime.

Purpose of the Study:

• To investigate HCSS particle self-assembly using more realistic soft shell potential profiles.
• To explore the structural diversity achievable by tuning density and soft shell characteristics.
• To assess the potential for fabricating exotic 2D structures via colloidal self-assembly.

Main Methods:

• Utilized minimum energy calculations.
• Employed Monte Carlo simulations.
• Investigated various soft shell potential profiles beyond the square shoulder model.

Main Results:

• Thin shell HCSS particles formed diverse structures (hexagons, chains, squares, rhomboids, zig-zags) by tuning density and soft shell profiles.
• Experimentally realistic linear ramp repulsions enabled the formation of honeycombs and quasicrystals (10-fold, 12-fold symmetry).
• Structural diversity is controllable via density and shell-to-core ratio (r1/r0).

Conclusions:

• Realistic soft shell potentials significantly expand the range of self-assembled structures from HCSS particles.
• Tuning particle properties offers a pathway to fabricating complex 2D materials.
• The findings suggest exciting possibilities for experimental colloidal self-assembly of exotic structures.