https://doi.org/10.1140/epja/s10050-024-01316-4
Regular Article - Theoretical Physics
The Jost function and Siegert pseudostates from R-matrix calculations at complex wavenumbers
Nuclear Physics and Quantum Physics, C.P. 229, Université libre de Bruxelles (ULB), 1050, Brussels, Belgium
Received:
24
January
2024
Accepted:
11
April
2024
Published online:
6
May
2024
The single-channel Jost function is calculated with the computational R-matrix on a Lagrange-Jacobi mesh, in order to study its behaviour at complex wavenumbers. Three potentials derived from supersymmetric transformations, two of which never previously studied, are used to test the accuracy of the method. Each of these potentials, with s-wave or p-wave bound, resonance or virtual states, has a simple analytical expression for the Jost function, which is compared with the calculated Jost function. Siegert states and Siegert pseudostates are determined by finding the zeros of the calculated Jost function. Poles of the exact Jost function are not present in the calculated Jost function due to the truncation of the potential in the R-matrix method. Instead, Siegert pseudostates arise in the vicinity of the missing poles.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2024. 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.
