https://doi.org/10.1140/epja/s10050-023-01015-6
Regular Article - Theoretical Physics
Semiclassical approximations of photoabsorption cross sections beyond the continuum threshold
1
Laboratoire de Chimie Théorique, Sorbonne Université and CNRS, 75005, Paris, France
2
Institut Universitaire de France, 75005, Paris, France
Received:
27
March
2023
Accepted:
21
April
2023
Published online:
5
May
2023
We develop semiclassical approximations for calculating photoabsorption cross sections beyond the continuum threshold in quantum many-body systems. These approximations use the fully quantum-mechanical Wigner function of the ground state and semiclassical expansions only for the part of the cross section depending on the continuum states, thus avoiding the difficult explicit calculation of the continuum states. Even though the approach is general, we test it in electronic-structure theory for the photoionization cross sections of the hydrogen and helium atoms. The results suggest that these semiclassical approximations can be used to obtain good estimates of cross sections at high energy.
Dedicated to the memory of Peter Schuck.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
