Dynamic transitions in a two dimensional associating lattice gas model

Area of Science:

• Statistical Mechanics
• Computational Physics
• Soft Matter Physics

Background:

• The associating lattice gas (ALG) model incorporates soft core interactions and orientational degrees of freedom.
• Competition between repulsive and attractive forces leads to distinct liquid and gas phases.

Purpose of the Study:

• Investigate the phase diagram and diffusion coefficient behavior in the ALG model.
• Identify anomalies in density and diffusion across different thermodynamic regions.
• Characterize dynamic transitions in particle diffusivity.

Main Methods:

• Monte Carlo simulations were employed to model the ALG system.
• Analysis focused on phase transitions, coexistence lines, and critical points (bicritical, tricritical).
• Diffusion coefficients were examined across the chemical potential-temperature phase diagram.

Main Results:

• Observed anomalies in density-temperature and diffusion coefficient-density relationships.
• Identified a bicritical point and a tricritical point, linked by a critical lambda-line.
• Discovered two dynamic transitions: fragile-to-strong across the lambda-line and strong-to-strong across the tau-line.

Conclusions:

• The ALG model exhibits complex phase behavior with multiple critical points and lines.
• Diffusivity shows distinct dynamic transitions related to crossing specific critical lines.
• Simulation results provide insights into the interplay of interactions and emergent phase properties.