  The recently discovered coexistence of multifragmentation and residue
production for the same total transverse energy of light charged particles can
be well reproduced in numerical simulations of the heavy ion reactions. A
detailed analysis shows that fluctuations (introduced by elementary
nucleon-nucleon collisions) determine which of the exit states is realized.
Thus we observe for the first time nonlinear dynamics in heavy ion reactions.
Also the scaling of the coexistence region with beam energy is well reproduced
in these results from the QMD simulation program.
