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Shedding light on few-body quantum dynamics by studying atomic collisions

The quantum-mechanical few-body problem has challenged physicists ever since the foundations of quantum theory were laid in the 1920s. Collisions of atoms, molecules, and their ions are particularly interesting realizations of this problem, because the interaction potentials are well known and the question of how to deal with the few-body character of the collision system under study is the only fundamental difficulty for theory. Given the abundance of available experimental data and the importance of understanding them not just for fundamental but also for applied reasons, there is considerable motivation to address this difficulty.
The objective of this talk is to illustrate these statements using examples drawn from recent research in the field. In particular, a time-dependent quantum-mechanical approach based on the concepts of density functional theory will be outlined and applied to three-electron collision systems involving helium and lithium atoms. It will be demonstrated that depending on the process under study the few-body problem presents itself as a more or less intricate one. I will discuss situations which reflect single-active-electron dynamics, independent-electron dynamics and more complicated, i.e., correlated, electron dynamics.