Colloquium on September 11, 2000MartinGutzwillerFellowship, Award CeremonyDominique Delande "Beyond periodic orbit theory and random matrix theory in atomic physics It is nowadays well established that the energy spectrum of a quantum chaotic system (in the semiclassical regime) is described on the one hand by random matrix theory for short energy range statistical properties, and on the other hand by periodic orbit theory for long energy range properties. However, in atomic systems, the interaction between an excited electron and the nucleus+inner electrons is singular. I will show how this leads to a breakdown of the semiclassical approximation as well as deviations from random matrix and periodic orbit theories, and how to repair these difficulties.  

