Modern aspects of the three-body Coulomb problems

We explore quantum aspects of characteristic, highly correlated configurations of doubly excited two-electron atoms, in one, two and three dimensions, along stable and unstable periodic orbits of the classical system. Comparing the autoionization rates of such configurations we find that the two dimensional restriction is in quantitative agreement with the real physical system, whilst the one dimensional model can underestimate the actual decay rates by orders of magnitude. We also study the influence of an additional electromagnetic field on the system. An accurate ab initio quantum treatment of the driven planar atom indicates the existence of nondispersive two-electron wave packets. These highly correlated wave packets arise as a quantum manifestation of regular islands in a mixed classical space, induced by nonlinear resonances between the external field and the unperturbed dynamics of the associated regular configuration of the atom.