[lammps-users] Question about re-define pair coefficient after generating restart files


After a couple of runs, I want to change the Lennard-Jone’s interaction parameters for one of the atoms in my simulation. I’ve read the tutorial saying that we could define the pair_coeff in both data.file and in.file. Since I’m reading everything from the restart file, I’m thinking of changing them in the in.file.

At the beginning I defined my Lennard-Jone’s potential parameters in the data file as:
1 0.0958 3.0335
2 0.1986 3.6242
3 … …
4 . … …
and I use pair_modify to take care of different combination of possible atom pairs.

I’m wondering if it is true that in the in.file, we could only define the L-J parameters as: atom1 atom2 epsilon sigma ?

I have 11 atom types, but I only want to modify the L-J for one of them. Is there an easy way to do it rather than specifying all the possible pairs this atom is involved in?

i.e. Atom type #2 is the one I want to change the LJ parameters. Do I have to do:

In the input script, you just define what you want to change. The rest will remain same whatever is stored in restart file.
Right Steve?

Vikas is correct. But you must insure that you make your
changes after the read_restart command. LAMMPS commands
execute sequentially. Read_restart will set all the pair coeffs
and wipe out any previous settings. You should also
read about mixing for I != J components. You can do that automatically
or override the default mixing. See the pair_modify command for details.