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

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1

Hi,

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:

2

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?

3

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.

Steve