Hi - please continue to post to the list, not to me.
I don’t think there is a way to do that from the input
script in LAMMPS. But if you want to edit one
of the granular pair styles, it sounds as easy as removing
the “meff” multiplier from a couple of equations in the
inner loop. E.g. maybe the ones for “damp” and the tangential
Maybe Dan can comment on that as an alternate model.
There are many different models for damping depending on assumptions about dissipation mechanisms (Hermann, Brilliantov, Tsuji, etc.; see Kacianauskas et al, Procedia Eng 102 (2015), p. 1415), but I’m pretty sure all of them have a mass dependence. Otherwise, you can imagine if you set a constant damping to get a reasonable coefficient of restitution for a small (low mass) particle, that same damping would have little effect on a high mass particle, so the large particle would have a very large coefficient of restitution (i.e. it would bounce like a rubber ball).