[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

Regards
Rajib

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.

Axel

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