Diffusion in Mesoscopic Lattice Models of Amorphous Plasticity

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Physics

Background:

• Amorphous materials exhibit complex plastic deformation under shear.
• Understanding particle diffusion is crucial for modeling material behavior.
• Discrepancies exist between particle-based and mesoscale models of amorphous plasticity.

Purpose of the Study:

• To investigate tagged particle diffusion in a mesoscale lattice model of sheared amorphous materials.
• To analyze the system-size dependence of diffusion coefficients in different time regimes.
• To resolve discrepancies in diffusion coefficient scaling between simulation types.

Main Methods:

• Utilized a mesoscale lattice model for sheared amorphous material under athermal quasistatic conditions.
• Analyzed tagged particle diffusion across short and long time scales.
• Examined the influence of interaction kernel details on diffusion behavior.

Main Results:

• Identified two distinct diffusive regimes: short-time and long-time.
• Short-time diffusion coefficient scales as D∼L^{1.05}, consistent with particle-based simulations.
• Long-time diffusion coefficient scales as D∼L^{1.6}, aligning with previous mesoscale studies.
• Interaction kernel details significantly impact long-time behavior, not short-time.

Conclusions:

• The D∼L^{1.05} short-time scaling reconciles differences between particle-based and mesoscale models.
• Mesoscale lattice models can accurately capture short-time diffusion dynamics.
• Long-time diffusion is sensitive to interaction kernel specifics, potentially leading to MSD saturation.