Can lammps combine fix move with dpd stat commands in Kremer-Grest model?

Hello everyone
I use lammps to build the Kremer-Great model for polymer melt, and use DPD thermostat instead of langevin equation

for some reasons, I change this model. I want to freeze some monomer, and run this model. So, I add command like this, and other commands is same:

  1. fix ID group-ID move linear 0.0 0.0 0.0 units box
  2. compute group-ID(which is free) temp

But the tempreture is lower than 1.0, and is about 0.92??

So, can lammps do this model?


If you are using pair dpd/tstat for thermostatting, it

operates on pairs of atoms and uses their relative

velocities. So I suggest you make (at least) 2 atom types.

One for frozen atoms and one for mobile atoms. You can

apply the Kremer/Grest model to both types and freeze

the one type. But I would only apply pair dpd/tstat to

the mobile type, so it is always working on pairs of mobile

atoms. The pair hybrid/overlay command can do this,

which is what you would normally use with dpd/tstat anyway.

Also, if you are computing temperature of mobile atoms

but some of them are bonded to frozen atoms, that might

affect their temperature. I.e. reduce it, since some of

the mobile atoms are not as “free” to move as they

would otherwise be.