ERROR: Temperature compute degrees of freedom < 0

Hello everybody,

I performed a search, I found two e-mails but they weren't useful,
unfortunately.

I attach the script which runs into this problem. It is clearly related to
the "fix rigid" command used.

It is a redeposition of a granular material in a box

curiously, this problem disappears if the number of particles in the
"BULK" is equal to 1000 (i just put 100 to study a smaller system)

Any hint to solve this issue would be really appreciated

​the default temperature compute in LAMMPS assumes point particles.
however, you have extended particles with additional degrees of freedom.
fix rigid takes that into account, hence the negative number of DOFs.

try inserting:

​compute t1 all temp/sphere
thermo_modify temp t1

​into your script to change the default temperature compute against one
that knows about extended particles.

axel.​