def find_smirnoff_params(ff) -> set:
    """Creates a set of all the smirnoff params, given a forcefield object. Loops over Bonds, Angles, ProperTorsions, ImproperTorsions, vdW only."""
    smirnoff_ids = set()

    handlers = ["Bonds", "Angles", "ProperTorsions", "ImproperTorsions", "vdW"]
    for handler in handlers:
        phandler = ff.get_parameter_handler(handler)
        for p in phandler.parameters:
            smirnoff_ids.add(p.id)

    return smirnoff_ids