Pressure showing as -nan

LAMMPS LAMMPS General Discussion
1

dear all，
I’m running a reaxff program but an error occurs.
ERROR on proc 1: Non-numeric atom coords - simulation unstable, I noticed the press showing as -nan, this may be the reason but I do not know how to fix it. Attached please find my in.file and forcefield file and log file. the OS I’m using is Ubuntu 20.04.5 LTS, the LAMMPS version is lammps-10Mar21.
Besides, if decreasing the quantity of CO to 300, the program will run well, it seems 350 COs is a special situation.

Thanks in advance,
mps
350CO-Fe2O3log1.lammps (4 KB)
in.Fe2O3-350CO (4.1 KB)
reax.FeOC (8.2 KB)

2

Hello,
Could it be that your atoms are overlapping in that case?
Simon

3

Perhaps not, I’ve checked the simulation box.,
Fe2O3-350CO.data (542.8 KB)
here is my data file.

4

Nevertheless, you obviously have forces that overflow and that usually means, you have atoms that are too close. Since you are using random placement when you are inserting the CO molecules, this is quite likely.

You can easily determine which atoms have overflowing forces by inserting:

dump   debug all custom 100 Fe2O3_350CO.lammpstrj type id x y z fx fy fz
run 0 post no

before the minimize command and then inspect the generated file. That will show “nan” forces for the affected atoms. My expectation is that the simulation can continue once the molecules are removed that these atoms are part of.

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