Must I use special-bond command for pcff force filed in msi2lmp examples?
That's really a force field Q. But I think the answer is yes,
that the PCFF ff is defined in a way that is consistent
with a LAMMPS setting of
special_bonds lj/coul 0.0 0.0 1.0
You should check this with the MSI manual or published
accounts of the ff.