| 1. |
- Jönsson, Per, et al.
(författare)
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An Introduction to Relativistic Theory as Implemented in GRASP
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Computational atomic physics continues to play a crucial role in both increasing the understanding of fundamental physics (e.g., quantum electrodynamics and correlation) and producing atomic data for interpreting observations from large-scale research facilities ranging from fusion reactors to high-power laser systems, space-based telescopes and isotope separators. A number of different computational methods, each with their own strengths and weaknesses, is available to meet these tasks. Here, we review the relativistic multiconfiguration method as it applies to the General Relativistic Atomic Structure Package [grasp2018, C. Froese Fischer, G. Gaigalas, P. Jonsson, J. Bieron, Comput. Phys. Commun. (2018). DOI: 10.1016/j.cpc.2018.10.032]. To illustrate the capacity of the package, examples of calculations of relevance for nuclear physics and astrophysics are presented.
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| 2. |
- Jönsson, Per, et al.
(författare)
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GRASP Manual for Users
- 2023
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- grasp is a software package in Fortran 95, adapted to run in parallel under MPI, for research in atomic physics. The basic premise is that, given a wave function, any observed atomic property can be computed. Thus, the first step is always to determine a wave function. Different properties challenge the accuracy of the wave function in different ways. This software is distributed under the MIT Licence.
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| 3. |
- Jönsson, Per, et al.
(författare)
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The Computational Atomic Structure Group : Code Development and Available Resources
- 2014
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Ingår i: Ninth International Conference on Atomic and Molecular Data and Their Applications: book of abstracts. ; , s. 113-113
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There is an increasing demand for accurate atomic data due to advancements in experimental techniques and investments in large scale research facilities. In astrophysics the quality and resolution of solar and stellar spectra has so improved that the accuracy of atomic data is frequently a limiting factor in the interpretation. Accurate atomic data are also required in plasma physics and in other emerging areas such as laser spectroscopy on isotope separators, X-ray lithography, and lighting research. The needs include accurate transition energies, fine- and hyperfine structures, mass- and field shifts as well as parameters related to interaction with external magnetic fields. Also there is a constant need for transition rates of different multipolarities between excited states. Data are needed for a wide range of elements and ionization stages. To meet the demands for accurate atomic data the COMPutational Atomic Structure (COMPAS) group has been formed. The group is involved in developing state of the art computer codes for atomic structure calculations in the non-relativistic scheme with relativistic corrections in the Breit-Pauli approximation [1] as well as in the fully relativistic domain. Here we describe new developments of the GRASP2K relativistic atomic structure code [2,3]. We present results for a number of systems and properties to illustrate the potential and restriction of modern computational atomic structure. Among the properties are transition rates, hyperfine- and magnetically induced rates, energy structure, and isotope shifts. We also discuss current code developments and plans for future work. The codes developed by the COMPAS group, along with detailed user manuals, are freely available at http://ddwap.mah.se/tsjoek/compas/ .
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| 4. |
- Petryla, Andrius, et al.
(författare)
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Theoretical and experimental studies of In I, Sn II, Sb III, and Te IV atomic properties
- 2012
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Ingår i: Europhysics Conference Abstracts;36C. - : European Physical Society. ; , s. 42-42
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We use relativistic multiconfiguration Dirac-Hartree-Fock and configuration interaction calculations to study 5s2nl and 5s5p2 configurations of In I, Sn II, Sb III, and Te IV. Energies, transition amplitudes, Land´e gJ-factors, and hyperfine constants are calculated using a correlation model that accounts for valence and core-valence correlation. Also spin- and orbital polarization effects are accounted for by single excitations from all core-shells to an increasing set of active orbitals. Transformed to the LSJ-coupling scheme, using the new features of the GRASP2K program, the calculated wave functions shed light on the difficulties in labeling some states due to the extensive 5s25d and 5s5p2 configuration interaction. Our results are compared with experimental values and values from relativistic many-body perturbation theory (RMBPT) and all-order single-double (SD) calculations. The theoretical work is complemented with experiment, and new hyperfine interaction constants are derived for several states in In I from high resolution Fourier Transform Spectra.
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