FW: Stress per atom units

Hi Steve and team,

I am a postgraduate researcher at University of Limerick in Ireland and I am using LAMMPS to put irradiated CNT ropes under tension.

I am outputting (dumping) cfg files containing stress per atom (in zz) every 1000 steps for each atom in the rope (I attach input file and one outputted cfg file). However, I am having difficulty understanding what the units are for the stress in zz for each atom (c_1[3]). According to the manual, for stress/atom, the units are a (pressure)*(volume) formulation and you divide by the volume/atom to get the stress for each atom. But the volume per C atom is 0.882e-29 m^3 and when the c_1[3] value is divided by this volume, you get a massive unrealistic stress value (1e35 Pa or something).

Do you know how to convert each individual c_1[3] value in the attached cfg file into stress values with units in GPa?


in.test (3.3 KB)

dump.202000.cfg (468 KB)

I am a postgraduate researcher at University of Limerick

To understand simulation output of stress
without attention to units is a mess.
See the units doc page
to lessen your rage,
and your problem should be solved, more or less.