[lammps-users] weighting coeffs for 1-4 atoms in different molecules

Hello,

I am wondering whether it is possible to set two different sets of
values of weighting coefficients. Say

    special_bonds lj 0.0 0.0 0.5 coul 0.0 0.0 0.83333333333

for molecule type A (or a group of molecules) and

    special_bonds lj/coul 0.0 0.0 0.5

for molecule type B.

Thanks,

Hello,

I am wondering whether it is possible to set two different sets of
values of weighting coefficients. Say

no. the list of scaling factors are global.
the neighbor list uses additional bits
in the neighbor list entries to signify
1-2, 1-3, or 1-4 neighbors.

axel.

Would this functionality be too involved to implement in lammps?

Would this functionality be too involved to implement in lammps?

at the level of neighbor lists. definitely, yes.

_but_ different 1-4 scaling is essentially nothing else
but a modification of the dihedral potential. you could
implement a custom dihedral style for that. similar to
the charmm angle style.

axel.

yes, if you want to change the neighbor lists.

If you really need this (it's an odd model that
wants two sets of these coeffs - that's like mixing
two force fields), then I suggest editing the
pair style file itself and twiddling the weighting
factors however you want once they are extracted
from the neighbor list.

Steve