[lammps-users] Size effect of a Single particle dynamics in free space

Dear LAMMPS user,
I am studying the dynamics of a tracer particle in a free space by varying the size of the particle using langevin thermostat. I am using an ellipsoid as an atom style. When I am varying the particle size, I am not seeing any change in the dynamics of the tracer particle.

Following is my script where I am varying different size in terms of effective interaction diameter,

For size=1sigma
pair_coeff 1 1 1.0 1.0 1.12
For size=5sigma

pair_coeff 1 1 1.0 5.0 5.60

I am using LAMMPS (Version 29 Oct 2020) in Ubuntu 18.04 LTS.

Am I missing something while varying size of the tracer particle? Your suggestions are highly appreciated.

Thank you in advance


What you are missing is, that it is completely irrelevant what atom_style you are using and what per-atom properties you are setting, if the pair style in use and the time integration/thermostat fix(es) do not use those properties and settings.


Also, if you have only a single particle, why should changing the pair_coeff settings change anything? There is nothing it is interacting with.