The anharmonic vibrator and rotor regions in nuclei are investigated in the framework of the interacting boson model using an ensemble of random one- and two-body interactions. We find a predominance of $L^P{=0\mathrm{}}^{+}$ ground states, as well as strong evidence for the occurrence of both vibrational and rotational band structures. This remarkable result suggests that such band structures represent a far more general (robust) property of the collective model space than is generally thought.

• Received 10 September 1999

DOI:https://doi.org/10.1103/PhysRevLett.84.420