SEMIQUANTAL DYNAMICS OF FLUCTUATIONS - OSTENSIBLE QUANTUM CHAOS

The time-dependent variational principle using generalized Gaussian tr ial functions yields a finite dimensional approximation to the full qu antum dynamics and is used in many disciplines. It is shown how these ''semiquantum'' dynamics may be derived via the Ehrenfest theorem and recast as an extended classical gradient system with the fluctuation v ariables coupled to the average variables. An extended potential is co nstructed for a one-dimensional system. The semiquantal behavior is sh own to be chaotic even though the system has regular classical behavio r and the quantum behavior had been assumed regular.