Reference to my earlier conversation on Tersoff Potential function, I believe, current version of LAMMPS doesn’t capture all the versions of Tersoff potential function. As a matter of fact, Tersoff gave 4 versions of potential function out of which only the two former versions are currently available in LAMMPS.
The potential function for SIC given by Tersoff in 1988 has been named as Tersoff_1 in LAMMPS & the second potential given by Tersoff in 1989 has been named as Tersoff_2.
Apart there were other two potentials also given by Tersoff in 1990 & 1994 which reveals different results especially coordination number & bond length but still all potential functions being used in practice depending on suitability.
So, the balance two versions are yet to be added to Lammps library. If you require, I can coordinate in this regard.