I am working on a problem where I will need to take the Tersoff Potential (and possibly another similar potential that isn’t implemented in LAMMPS - the Erhart-Albe potential) and make the small-separation behavior ‘stiffer’ by using the Ziegler-Biersack-Littmark (ZBL) potential.
The way this has been done before is by smoothly connecting the two potentials using a Fermi function-like function (using the Tersoff potential as an example):
U_combined (r_ij) = (1 - F_f) U_ZBL(r_ij) + F_f U_Tersoff(r_ij)
where F_f is the fermi like function.
I have looked at the documentation for the hybrid and hybrid/overlay pair styles - but these don’t really seem to fit the bill (assuming I implemented the ZBL potential and the E-A potential). However, rather than implementing the whole thing, perhaps setting up a table type may be easier - but it appears this is only intended for ‘real’ 2-body potentials (i.e. not a bond order potential like Tersoff).
Any thoughts on how would be best to proceed? Seems like the best option is to implement the hybrid potential directly.
David E. Farrell
email: [email protected]…435…