[lammps-users] Error related to group ID while using "fix heat" for thermal transport simulations

Steve, LAMMPS users,
I am trying to use fix heat with the script below and the attached data file in order to run a thermal transport simulation.
The error I get is that the “fix group ID cannot be found”. In the lines highlighed in bold below (fix 7 2 heat 1 0.0000004545 and fix 8 3 heat 1 -0.0000004545), I was trying to specify that heat should be added to atoms with group ID 2 (i.e. atoms with group ID 2 in the attached data file) and removed from atoms with group ID 3.
Please let me know what I am missing.


96-SiforNVE.txt (451 KB)

Steve, LAMMPS users,

96-SiforNVE.zip (184 KB)

In your input script, I dont see any group commands.

Vikas is correct - which atoms do you think are in group 2?
If you mean type 2 atoms, then you would have to put them
in a group to use them with fix heat command.


I am now specifying the type 2 and type 3 atoms as separate groups and then using fix heat. I am currently running these simulations. I wanted to confirm a couple of aspects:

  1. For monitoring the energy exchanged, is f_2 the scalar to print out/monitor (assuming the ID number for the fix heat is 2)?
  2. The eflux parameter in fix heat is in energy/time units. If I want 5 eV total energy exchanged over 1100 psec of simulation time(metal units), should eflux be 5.0/1100.0 irrespective of what value I use for N?