[lammps-users] Angle of reversible bond

Hello, everybody:

For a system containing reversible bonding (probably using Morse
potentials or a simple attractive form), while there are breaking and
forming of such kind of bond, I also want to restrain the angle of the
bond. Is this feasible with LAMMPS? Any suggestions? Thanks in advance!

I don't know how you are "breaking" a bond, but if you don't
do anything to the angle term, then it will remain in force.

However, I don't know what it means physically to break a bond, but
keep the angle intact.


Thank you, Steve.
Physically, what I am dealing with is reversible bonding like hydrogen
bonding, but with larger association energy, hence longer lifetime (0.1
second or so). Althrough the associcating energy ( much lower than
covalent bonding energy) is the same during the simulation, the atom may
escape when the temperature is high, that's, the "bond" is broken. At
the same time, new bonds come into being when such kind of atoms
encounter each other.

In the frame of LAMMPS, I choose Morse potentials for this reversible
bonding, is this a good choice? My concerning is, is it feasible to
contol the direction of such reversible bonding by adding restraint to
the angle or dihedral where it is involved. As you can see, those
"bonds" are not fixed.

Hope it is clear, thanks again.

If you mean use the Morse pair potential to define a "bond" when
2 atoms get close together, then OK. If you mean a Morse bond
potential (both exist in LAMMPS), then it will not break like
you are envisioning.

Whether you layer angle potentials on top of that is a separate issue.