Structure, compressibility factor, and dynamics of highly size-asymmetric binary hard-disk liquids

Area of Science:

• Soft Matter Physics
• Computational Materials Science
• Statistical Mechanics

Background:

• Understanding the behavior of mixtures with significant size disparity is crucial for designing new materials.
• Binary hard-disk systems serve as fundamental models for studying complex fluid phenomena.

Purpose of the Study:

• To investigate the impact of varying small disk area fraction on the structure, compressibility, and dynamics of highly size-asymmetric binary hard-disk liquids.
• To elucidate the mechanisms behind non-monotonic compressibility and reentrant dynamic transitions.

Main Methods:

• Event-driven molecular dynamics simulations were employed.
• Analysis included static pair correlations, higher-order correlations, bond-orientation correlation functions, and diffusion coefficients.

Main Results:

• Static pair correlations of large disks are weakly affected, while higher-order correlations and correlation length are significantly influenced by small disks.
• Compressibility factor exhibits non-monotonic behavior (decrease then increase) with increasing small disk fraction.
• Large disks show monotonic increase in relaxation time, with reentrant behavior at high large disk fractions.
• Small disks exhibit concave-to-convex crossover and logarithmic decay in relaxation.
• Diffusion of both species is suppressed, with small disks showing power-law-like diffusion at high area fractions.

Conclusions:

• The study demonstrates generic dynamic features in highly size-asymmetric binary mixtures, including reentrant glass transitions and precursors to localization transitions.
• The findings provide insights into the complex interplay between size asymmetry and emergent collective behaviors in soft matter systems.