Dear Lammps users,
I need Lammps not to ignore special_bonds settings for many-body potentials. Can someone please point me which subroutine(s) and variables I should modify? I tried myself, but no success. Any help/suggestion will be greatly appreciated.
IMPORTANT NOTE: These weighting factors are NOT used by pair styles that compute many-body interactions, since the “bonds” that result from such interactions are not permanent, but are created and broken dynamically as atom conformations change. Examples of pair styles in this category are EAM, MEAM, Stillinger-Weber, Tersoff, COMB, AIREBO, and ReaxFF. In fact, it generally makes no sense to define permanent bonds between atoms that interact via these potentials, though such bonds may exist elsewhere in your system, e.g. when using the pair_style hybrid command. Thus LAMMPS ignores special_bonds settings when manybody potentials are calculated.
Thanks,
Payel
Dear Lammps users,
I need Lammps not to ignore special_bonds settings for many-body
potentials.
what for? do you *want* LAMMPS to produce horribly wrong results?
Can someone please point me which subroutine(s) and variables I
should modify?
you have to write new, modified versions of those many-body potentials.
I tried myself, but no success. Any help/suggestion will be
greatly appreciated.
what did you try?
let me just explain in detail what happens. if you do define explicit
bonds/angles/dihedrals LAMMPS will cull all entries from the neighbor
lists that are fully excluded and "unflag" those that have a factor of
1.0. for the remaining entries a flag is added to the neighbor index,
that indicates whether a given pair is a 1-2, 1-3 or 1-4 neighbor. the
manybody potentials simply remove this flag.
to have them make use of that flag, you have to change the potential
wherever this is used. *but* _you must not have any fully excluded
entries_ as well, since the manybody potentials need them to compute
bond order and angle terms and so on.
it is the latter process that is fundamentally incompatible with the
concept of excluded bonded interactions that makes your questing such
a very bad idea.
axel.