Dear Lammps users,

I have a query regrading the thermo command. I have been trying to learn how to use the “heat” “fix” command to perform various non-equilibrium simulations. In my latest test however I have noticed that the thermo command does not appear to be working when used in conjunction with this “fix”. I have attached my input for the mentioned case.

To expand on the specifics of the simulation, I create a box of LJ particles on an FCC lattice which is 18x18x7 lattice units and then proceed to equilibriate it at T=1.0 (LJ units) in the NVT ensemble. I then switch to NVE and add and removed heat each time step from 4 spherical regions which I define earlier in the script. When I attempt to run this part of the simulation the thermo command appears to have no effect as the various information it usually prints to standard output only appears for the zeroth step and no subsequent steps.

Many thanks in advance, Jeff.

in.spheres (905 Bytes)

The problem is the reset_timestep command, you can't use it with a
dump command that is writing in a file at the same time the
reset_timestep is used.

If you update your LAMMPS you can make this code run, this restriction
was removed (8 Jun 2012 -

Or you can just get rid of the reset_timestep command (is it really useful?).

One more thing, there's no need to define a group with all atoms,
there is a default 'all' group that contains all atoms.

Rodrigo Freitas

Rodrigo is correct that there was a recent change with allowing
dump files to remain open even if you reset the timestep.
However, I see there is a bug with the logic this introduced
which can affect the thermo and dump output, which you ran into.
I'll post a patch today ...