[lammps-users] Implementing UFF on lammps...

Hello everyone,

Does any of you know about some force field different from AMBER or CHARMM implemented on LAMMPS?
I’m interested in the Universal Force Field(UFF) because my research involve organic/metal systems combined
so I need a force field that tries to describe them both accurately. This may open the oportunity
to mingle potentials such as EAM with a force field and see how well this combination describe organo/metallic systems.

I couldn’t find any add-on or plugin out there, so I’ve been trying to do it on my own but at this crude stage
I need some aid in order to put things clear and help me determine how viable would be to build this force
field inside LAMMPS.

Constructing both the bond stretch and angle bend terms of UFF should represent not a problem because are similar to
previously defined potential already in LAMMPS. When it comes to the torsion and inversion terms
one question has risen. Since both of them are 4-atoms type potential, do I have to take special consideration
for the hybrid option on dihedral_style to work? and is there a way to overload the dihedral to understand
4-atoms bonded non-linearly? Also something that would save a lot of time when coding or defining the topology file is, whether it’s possible or not
to exclude atoms linked by a bond or by means of an intermediary atom from, for example, a lennard jones interaction.

For the moment that’s it. I would really appreciate your comments and if possible some hints
on people trying to do the same thing.

Thanks in advance,

I think you mean dihedrals and impropers, the latter is
4 non-linear atoms. LAMMPS has both. See the
improper_style command.