Diffusion and interactions of interstitials in hard-sphere interstitial solid solutions.

Area of Science:

• Computational Materials Science
• Statistical Mechanics
• Condensed Matter Physics

Background:

• Understanding the behavior of interstitial particles is crucial for designing advanced materials.
• Hard-sphere models provide a fundamental framework for studying particle dynamics and interactions in solid solutions.
• Accurate prediction of diffusion coefficients is essential for material property characterization.

Purpose of the Study:

• To investigate the dynamics and interactions of interstitial particles within hard-sphere interstitial solid solutions.
• To calculate free-energy barriers for interstitial diffusion across various size ratios and densities.
• To assess the applicability of classical transition state theory (TST) for predicting interstitial diffusion.

Main Methods:

• Utilized computer simulations to model hard-sphere interstitial solid solutions.
• Calculated free-energy barriers for interstitial particle diffusion.
• Applied classical transition state theory and event-driven molecular dynamics simulations to determine diffusion coefficients.

Main Results:

• Predicted diffusion coefficients using TST showed excellent agreement with molecular dynamics simulations.
• Interstitial-interstitial interactions were found to be nearly ideal, excluding excluded volume effects.
• Established an empirical relationship linking large-particle fluctuations to interstitial diffusivity.

Conclusions:

• Classical transition state theory effectively captures interstitial dynamics in the hard-sphere model.
• The study provides insights into the nature of interstitial interactions and their impact on diffusion.
• Interstitial diffusivity can be reliably inferred from large-particle fluctuations, offering a novel predictive approach.