EXTRACTING THE DYNAMICS IN CLASSICALLY CHAOTIC QUANTUM-SYSTEMS - SPECTRAL-ANALYSIS OF THE HO2 MOLECULE

We present a scaling technique to analyze quantum spectra, i.e., to ob tain from quantum calculations detailed information about the underlyi ng important classical motions. The method can be applied to a general quantum system without a classical scaling property. A demonstration on the conventionally unassignable vibrational spectrum of the HO2 rad ical reveals remnants of classical broken tori embedded in the chaotic phase space and leads to a new assignment of spectral patterns in ter ms of classical Fermi resonances between the local mode motions. The s caling technique also allows to investigate the statistical properties of level spacings at fixed energies. The nearest neighbor spacing dis tribution of the HO2 molecule undergoes a transition from mixed phase space behavior at low energies to the Wigner distribution characterist ic for chaotic systems at energies near the dissociation threshold. (C ) 1997 American Institute of Physics. [S0021-9606(97)03741-0].