[lammps-users] coul forces/fix

Hi all. I'm writing a fix that needs the force on a particle
from just the coulomb interaction. I was thinking about
adding a new atomic array, but don't know how to do this
without breaking future updates. That is, without modifying
the atom, compute, pair style, and pppm files. Any suggestions?

Fixes can create/store their own per-atom vectors/arrays
and maintain them separate from atom and atom_vec.
How and where in the code are you intending to compute
the array that stores Coulomb forces per particle?


Hi Steve. It's my understanding that pair_lj_cut_coul_long.cpp
calculates the short range part of the coulomb interaction and
pppm.cpp calculates the long range (when using that pair
style/k-space method). I was thinking I would have an atomic
array that could be used by those two routines, and accessed
by my fix. I was hoping to add files instead of alter existing
ones. I update frequently and don't want to have to change
those files each update.

If you want pair*long.cpp and pppm.cpp to tally Coulomb
forces, I don't seen any way around editing those files. Once
those values are computed and added to the total force,
they are gone.