Error: Fix bond/break requires special_bonds = 0, 1, 1

Hi,

I’m trying to run lammps with the following command.

fix bb7 ligand bond/break 10 7 0.5 prob 0.5 49829

I got this error “Fix bond/break requires special_bonds = 0,1,1 (…/fix_bond_break.cpp:138)”. The erros is a restriction of the current fix bond/break implementation as the lammps errors page says.

To fix it, I try to add a special_bonds command

special_bonds lj 0 1 1 angle yes dihedral yes

But I still get this errors. Adding the special_bonds does not work. I don’t know why. Would you please tell me how to fix this?

Hi ZHANG,

Try:

special_bonds lj 0.0 1.0 1.0 coul 0.0 1.0 1.0 angle yes dihedral yes

Thanks.

CW JANG

Thanks. It works now. I don’t involve the Coulombic interaction in the simulation. So I think it’s not necessary to add it in the special bonds.

Thanks. It works now. I don't involve the Coulombic interaction in the

do you mind letting us know, why does it work now?

simulation. So I think it's not necessary to add it in the special bonds.

two comments:

1) it is not fix bond/break, but the physics of your model that
determines what settings for special_bonds you need to use.
2) the error message you report is from an outdated LAMMPS version.
the restriction it warns about doesn't exist anymore, IIRC.

axel.