How to dump out per-atom force from pairwise interaction between certain types of atoms

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1

Dear LAMMPS users,

I know that the question I am going to ask has been asked before. But, this question was asked four years and I thought that a solution might have been introduced during the past years that I am not aware of.

Lets assume that there are type 1 and type 2 atoms in the system that are interacting with each other by Lennard-Jones (LJ) pairwise potential. There are interactions between type 1 atoms which is described by REBO potential. How can I dump the forces per atom of type 1 which are due to only LJ pairwise interactions in an output file?

I tried the following commands, but I think they are not appropriate for my purpose. I am saying this, because of the results I observed.

fix FPA type1 store/state ${print_frq} fx

compute FPA type1 pair/local force fx fy fz

The best,

Farshad

2

Hi Farshad,

You could do a rerun, I think:

Step 1) run the simulation with the full potential (LJ+REBO), writing a dump file with the positions
Step 2) use the rerun command on that dump file, with only the LJ potential defined
Step 3) Output the per-atom forces (now only due to the LJ potential) using a second dump

Thanks,

Niall