IFF PCFF HeinzMishraLinEmami model for homogeneous interatomic interactions


I am writing in order to kindly ask about the LAMMPS PCFF bonded force-field combined with IFF non-bonded 9-6 Lennard-Jones potentials for metal interactions v000 potential.

I am trying to use the potential: Short KIM ID SM_039297821658_000 to simulate homogeneous atomic interactions, i.e., interactions between only a single type of atoms.

After finding out the atomic type I need by looking up the Pearson symbol, I am not being able to find the bond, angle and dihedral types corresponding to the bonds between oc8 and itself, or any other homogeneous interactions for this matter, in the parameters file for this potential ( https://openkim.org/files/SM_039297821658_000/IFF-supermodel.params ).

These are needed since as it was clarified to me in: Using PCFF via OpenKIM - #3 by serge
I need to specify the specific type of atoms, bonds …etc from the parameters file.

All I see are parameters for heterogeneous bonds, angles and dihedrals.

I know from the description, and from a few papers which use this potential that I checked, that the above potential is mainly used for interface simulations. I was wondering however if it had the capability of simulating mono-atomic systems and if so what modifications should be introduced to the parameters file.

Thanks in advance,
Best Regards.

Hi Serge,
Sorry for the slow response on this. I checked with Hendrik Heinz who developed this potential, and this is what he said:

"In the clay structure, where we have these types (ay1, ay2, etc), there are no direct bonds ay1-ay2 (which are aluminum), they are all linked via oxygen atoms such as ay1-oy4, ay1-oy5, etc.

The same is true for oc8 with oc8 etc. They all follow a model structure that has specific bonds only. In both PCFF and CHARMM, we would find similar situations, say, there are types for hydrogen bonded to carbon such as CH3 in a methyl group, (h-c), and there will be no h-h bonds included, for example.

So the bonds that are defined are specific to one molecular structure, or a certain group of molecular structures."


Thanks Dr. Tadmor, this clarified the answer.

Best Regards.