Classical, semi-classical and quantum theories for strongly perturbed, nonlinear oscillators using a variety of novel theoretical approaches will be employed to understand the quantum processes that mimic classical chaos. Localization of wave functions and the striking phenomenon of "scars" associated with unstable, classical periodic orbits will be investigated as mechanisms which suppress classical chaos quantum mechanically. Systems to be studied include Rydberg atoms in microwave and strong magnetic fields, and inelastic and reactive scattering in chemistry.
