I’ve been having some trouble employing bonded atoms and pairwise potentials simultaneously, and I think my problem may be a result of my confusion of how LAMMPS implements these difference interactions.
It was my original understanding that if a bonded atom type also has a pair_style associated with it, the resulting interaction potential would be a combination of both the bonded potential, and the pairwise interaction. For instance, if two atoms of type “1” were bonded by a FENE bonded, but the 1 - 1 pair interaction was of type LJ, then both potentials would be used during the integration. Is this correct?
Another way of asking my question is asking whether these two statements would produce the same result:
First:
bond_style fene
bond_coeff 1 30.0 1.5 0.0 0.0
pair_style lj/cut 2.5
pair_coeff * * 1.0 1.0 2.5
Second:
bond_style fene
bond_coeff 1 30.0 1.5 1.0 1.0
Thanks for the help in advance! I will provide more details if needed, depending on how this question is answered.
I've been having some trouble employing bonded atoms and pairwise potentials
simultaneously, and I think my problem may be a result of my confusion of
how LAMMPS implements these difference interactions.
It was my original understanding that if a bonded atom type also has a
pair_style associated with it, the resulting interaction potential would be
a combination of both the bonded potential, and the pairwise interaction.
For instance, if two atoms of type "1" were bonded by a FENE bonded, but the
1 - 1 pair interaction was of type LJ, then both potentials would be used
during the integration. Is this correct?
no. at least not be default. the typical way how classical force
fields are implemented is to _exclude_ non-bonded interactions
for pairs of atoms that have a bond, an angle, or an dihedral angle
interaction. however, there are some tweaks to that for different
models and types of interactions. sometimes the non-bonded
interactions are included with a scaling factor, and - to make
matters even more complicated - sometimes those factors are
different for coulomb and non-coulomb interactions.
the special_bonds command in lammps allows to control
this behavior in the way you like.
Another way of asking my question is asking whether these two statements
would produce the same result:
First:
bond_style fene
bond_coeff 1 30.0 1.5 0.0 0.0
pair_style lj/cut 2.5
pair_coeff * * 1.0 1.0 2.5
Second:
bond_style fene
bond_coeff 1 30.0 1.5 1.0 1.0
no.
axel.