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The Theory of TwoElectron Atoms: From the Ground State to Complete Fragmentation
Tanner, Gregor; Richter, Klaus; Rost, JanMichael
HPLBRIMS9817
Keyword(s): twoelectron atoms; quantum chaos; electron correlation; review
Abstract: The evolution of understanding and predicting spectra of twoelectron atoms including doubly excited resonance states which are strongly influenced by correlated electronelectron dynamics is reviewed. In a first part we summarize the historical development and introduce common techniques to measure and calculate twoelectron atom states. Part two gives an introduction into approximate quantum methods developed for twoelectron atoms, in particular adiabatic and group theoretical approaches. These methods explain and predict the striking regularities of twoelectron resonance spectra by identifying approximate quantum numbers corresponding to collective, correlated electronpair dynamics. The quantum numbers are very different from the independent particle classification, suitable for low lying states in atomic systems, only. Part three describes modern semiclassical concepts and their application to twoelectron atoms. Simple interpretations of the approximate quantum numbers can be given in terms of a few key periodic orbits of the classical three body problem. Qualitative and quantitative semiclassical estimates for doubly excited states are obtained for both, regular and chaotic classical twoelectron dynamics using modern semiclassical techniques. Notes: Klaus Richter, Max Planck Institut fur Physik Komplexer Systeme, Nothnitzer Str. 38, D01187 Dresden, Germany. Jan Michael Rost, Fakultat fur Physik der Universitat Frieburg, Hermann Herder Str. 3, D79104 Freiburg, Germany
84 Pages
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