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Discontinuous molecular dynamics simulations in an external field: Application to two-dimensional ferrofluids
Matthew A Dorsey1, Carol K Hall1
1North Carolina State University, Chemical and Biomolecular Engineering, Raleigh, North Carolina 27606, USA.
Physical Review. E
|February 20, 2025
Summary
We developed a new stochastic method to simulate magnetic fields in coarse-grained models using discontinuous molecular dynamics (DMD). This method accurately reproduces system magnetization, crucial for understanding magnetic colloid behavior.
Area of Science:
- Computational Physics
- Materials Science
- Statistical Mechanics
Background:
- Coarse-grained models are essential for simulating complex systems like magnetic colloids.
- Simulating the effects of external magnetic fields on these models presents computational challenges.
Purpose of the Study:
- To introduce a novel stochastic method for incorporating external magnetic fields into discontinuous molecular dynamics (DMD) simulations.
- To validate this method using a 2D coarse-grained model of magnetic squares.
Main Methods:
- A stochastic approach applying impulses to charges within square-shaped colloidal particles was developed.
- Particle momentum was updated based on Maxwell-Boltzmann distribution and field direction.
- External field strength was correlated with interaction frequency, derived from Newton's laws of motion.
- Simulations utilized an Andersen thermostat for temperature control.
Main Results:
- The stochastic simulation method successfully reproduced net system magnetization.
- Observed magnetization closely matched the 2D Langevin function.
- Constant simulation temperature was maintained throughout the experiments.
Conclusions:
- The developed stochastic method is effective for simulating external magnetic fields in coarse-grained magnetic colloid systems.
- This technique provides accurate magnetization predictions while maintaining thermal stability.
- The method offers a valuable tool for computational studies in magnetism and soft matter.
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