Problem with brownian dynamics in lammps

I’m performing some simulations of brownian dynamics on lammps (version 22Aug2018), using the fix langevin command followed by a fix nve/sphere disc for the integration.
What I found is that also with extremely low values of Tstart=Tstop in the fix langevin, the system of 2d discs flows, having an high value of the mean square displacement.
Looking at the output what I see is that the temperature of the system is not kept at the value I set via the fix langevin.
How can I solve this problem? I expect that my system is not flowing for low values of T, if T does not change during the integration process.


Linda Ravazzano
PhD Student

Physics Department

University of Milan

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Universita` degli Studi di Milano - codice fiscale 80012650158

Please provide an input deck that demonstrates the issue. Axel.