Can fix bond/react work in REAXFF ?
No
Why can’t we usenew bond order description to specify the initiator atoms?
and we can avoid assigning new force fields to the reacted atoms.
Fix bond/react depends on an explicit bond topology which it can change. That does not exist in ReaxFF where the bond topology is dynamic and implicit and thus not accessible.
Apart from that, it doesn’t even make sense on a conceptual level.