Random sequential adsorption of particles with tetrahedral symmetry

Area of Science:

• Physics
• Materials Science
• Computational Chemistry

Background:

• Random sequential adsorption (RSA) is a fundamental process for creating disordered materials.
• The geometric symmetry of constituent particles significantly influences the packing density of jammed solids.
• Understanding jamming transitions is crucial for designing materials with specific properties.

Purpose of the Study:

• To investigate the effect of symmetry transitions (tetrahedral to octahedral) on jammed packing densities.
• To identify the optimal solid geometry for achieving the highest packing density in RSA.
• To characterize the density distribution within these random packings.

Main Methods:

• Simulating random sequential adsorption (RSA) of polyhedral solids derived from cubes.
• Analyzing the resulting jammed packings for density and structural properties.
• Calculating the density autocorrelation function to understand spatial correlations.

Main Results:

• Octahedral symmetry generally leads to lower packing densities compared to tetrahedral symmetry.
• The lowest density was observed for packings composed of tetrahedra.
• A modified tetrahedral solid, with slightly cut vertices and edges, yielded the densest packing (θmax=0.41278±0.00059).
• This density surpasses that of spheres or cuboids but is less than that of ellipsoids or spherocylinders in RSA.

Conclusions:

• The transition from tetrahedral to octahedral symmetry impacts packing density, with tetrahedral forms generally being denser.
• The densest packing is achieved by a specific, near-tetrahedral shape, highlighting the sensitivity of packing to geometry.
• The density autocorrelation function indicates that these packings behave like typical random media with short-range correlations.