Force Fields for Molecular Dynamics Simulations of Charged Dust Particles with Finite Size in Complex Plasmas

TL;DR

This paper introduces a new force field model for molecular dynamics simulations of finite-sized charged dust particles in complex plasmas, ensuring realistic particle contact behavior and analyzing transport properties under various conditions.

Contribution

A novel scheme for force calculation that prevents particle overlap and accurately models interactions in dusty plasma MD simulations, including effects of magnetic fields.

Findings

Finite particle size significantly affects transport properties at low coupling.

The model accurately reproduces pair distribution functions with contact constraints.

Magnetic fields influence shear viscosity and thermal conductivity in dusty plasmas.

Abstract

To exclude collisions leading to the overlap of finite-sized charged particles in molecular dynamics (MD) simulations in systems like complex (dusty) plasmas, we developed a scheme to generate a pair interaction force functionally depending on the pair distribution of particles. This ensures that the pair distribution function drops to zero at distances between particles corresponding to the point where the surfaces of two particles come into contact. The presented model has a wide utility for the description of various processes in dusty plasmas. As an example, using the non-equilibrium MD method, we performed calculations of the shear viscosity and thermal conductivity of charged spherical particles interacting via screened Yukawa potential. The role of finite particle size was found to be particularly important for small values of the coupling parameter, i.e., for gas-like and weakly correlated liquid-like systems. Furthermore, we have analyzed the shear viscosity and thermal conductivity in the presence of an external uniform magnetic field.