PHASE-SPACE DISTRIBUTIONS AND SPECTRAL PROPERTIES FOR NONHYDROGENIC ATOMS IN MAGNETIC-FIELDS

We present here the first study of the quantum phase-space behaviour (Wigner functions) for non-hydrogenic atoms in magnetic fields as well as a comprehensive study of spectral properties. We consider primarily an energy regime (scaled energy -0.5) where hydrogen is near-integrable and hydrogenic wavefunctions would be localized on tori. We find that the quantum energy level statistics for non-hydrogenic atoms are at the 'chaotic' (Wigner) limit. However, the quantum phase space distributions, contrary to what one would expect if the underlying classical motion were chaotic, remain dominated by torus-like structures. But the wavefunctions do explore a larger fraction of phase-space than in the hydrogenic case where, in the integrable regime, Wigner wavefunctions are generally localized on a single torus. Due to the non-semiclassical nature of the core they are localized on more than one torus; additional structures other than the tori are also present. Possible interpretations of the results in terms of models of the underlying classical dynamics are discussed.