A Gaussian wave packet centered on a classical trajectory spreads too much over the energy surface by the Ehrenfest time, causing the Ehrenfest theorem to break down

One difference between classical chaotic dynamics and quantum dynamics is that the state space of the former supports fractal structure while the state space of the latter does not. A second difference is that classical chaotic dynamics has a continuous energy spectrum associated with its motion. As previously noted, classical chaos is considered to be a property of bounded macroscopic systems. In comparison, the quantum dynamics in bounded, isolated systems has a discrete energy spectrum associ