Addendum: Chaos around a H\'enon-Heiles-Inspired Exact Perturbation of a   Black Hole
  We find that the model of a black hole plus an exterior halo of quadrupoles and octopoles recently proposed by us is more chaotic than previously detected. In fact, the quadrupolar component gives rise also to a chaotic behavior, found after further numerical search. This fact reinforces even more the role of chaos in relativistic core--halo models. 
Werner M. Vieira and Patricio S. Letelier