About MM3

I was wondering if anyone has had some experience using the MM3 force
field with lammps. And I am trying to simulate something using MM3 or
MM+ force fields. Is this implemented in Lammps? If not, can I make
this force field by assigning bond_coeff and everything required from
my input script?
Thank you very much!

I was wondering if anyone has had some experience using the MM3 force
field with lammps. And I am trying to simulate something using MM3 or
MM+ force fields. Is this implemented in Lammps? If not, can I make
this force field by assigning bond_coeff and everything required from
my input script?

matching atoms to types and assigning the corresponding force field
parameters, is generally a pre-processing step. LAMMPS doesn't do
this. whether it is possible to use LAMMPS for a specific force field
depends on the various functional forms required by this force field
and whether LAMMPS has an implementation for those. you have to look
up the publications describing your desired force field and compare
the potential functions against those that LAMMPS provides. in a
pinch, you may also be able to use tabulated potentials (but they
usually require much more care and testing to get them to work
reliably and correctly).

axel.