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Increase in rod diffusivity emerges even in Markovian nature
Fumiaki Nakai1, Martin Kröger2,3, Takato Ishida1
1Department of Materials Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan.
Physical Review. E
|May 18, 2023
Summary
Rod-shaped particles show increased diffusivity with higher matrix density, contrary to prior beliefs. This phenomenon occurs even without kinetic constraints, suggesting a new understanding of particle movement in dense environments.
Area of Science:
- Physics
- Materials Science
- Statistical Mechanics
Background:
- Rod-shaped particles in matrices can show increased diffusivity with matrix density.
- This phenomenon was previously attributed to kinetic constraints and tube models.
Purpose of the Study:
- To investigate the underlying mechanisms of increased rod diffusivity in dense media.
- To determine if kinetic constraints are essential for this observed phenomenon.
Main Methods:
- Utilized a kinetic Monte Carlo scheme with a Markovian process.
- Simulated a mobile rodlike particle in a sea of immobile point obstacles.
- Ensured gaslike collision statistics to minimize kinetic constraints.
Main Results:
- The unusual increase in rod diffusivity was observed even without kinetic constraints.
- This effect emerged when the particle's aspect ratio exceeded a threshold of approximately 24.
- Demonstrated that kinetic constraints are not a prerequisite for enhanced diffusivity.
Conclusions:
- The observed increase in rod diffusivity is not solely dependent on kinetic constraints.
- Particle shape (aspect ratio) plays a crucial role in anomalous diffusion.
- This finding challenges existing models and suggests new avenues for understanding particle transport in complex media.
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