Special bonds when using pair style table

LAMMPS LAMMPS Beginners
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1

Hi everyone,

my name is Daniele.

I’m running simulations with LAMMPS.
In my simulations I use a tabulated potential.
My question is relative to the usage of special_bonds in this situation.
Since I’m giving a tabulated potential LAMMPS won’t be able to recognise the coulomb and lj part. So how the special_bonds command effect this ?

Is my understanding that in this case the special_bonds command won’t have any effect an LAMMPS will compute all the pairs interactions 1-2, 1-3 and 1-4.
I wuold like to exclude only the 1-2 interaction with this tabulated potential but as far as I understand even if LAMMPS compute them the results shoud be fine because it is just calculating meaningless interaction that won’t effectively affect the dynamic of the problem since the two particles are bonded togher
Same argument would apply in the usage of pair_modify special command.

Did I undestand right about the funcion of those commands ?
Sorry if the question is too silly.

Many thanks in advance

Daniele

2

Pair style table is treated as LJ type potential.

That is not correct.

Also that is not correct.

No.

What should be excluded is determined by the force field you are using. For force fields with bonded interactions, usually all 1-2, 1-3, and 1-4 non-bonded special pairs should be excluded, since the corresponding bonded interactions are usually parameterized without considering any contribution from non-bonded interactions. So excluding only 1-2 interactions would be only valid for systems like bead-spring polymers.

3

@akohlmey Many thanks for your answers. That is very clear now !

Daniele