Per Jönsson
YOU?
Author Swipe
View article: <i>Ab initio</i> multiconfigurational calculations of experimentally significant energy levels and transition rates in Lr i ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Z</mml:mi> <mml:mo>=</mml:mo> <mml:mn>103</mml:mn> </mml:mrow> </mml:math> )
<i>Ab initio</i> multiconfigurational calculations of experimentally significant energy levels and transition rates in Lr i ( ) Open
Large-scale multiconfigurational calculations are conducted on experimentally significant transitions in Lr I and its lanthanide homologue Lu I, exhibiting good agreement with recent theoretical and experimental results. A single reference…
View article: Graspg -- An extension to Grasp2018 based on Configuration State Function Generators
Graspg -- An extension to Grasp2018 based on Configuration State Function Generators Open
The Graspg program package is an extension of Grasp2018 [Comput. Phys. Commun. 237 (2019) 184-187] based on configuration state function generators (CSFGs). The generators keep spin-angular integrations at a minimum and reduce substantiall…
View article: Natural Orbitals and Targeted Non-Orthogonal Orbital Sets for Atomic Hyperfine Structure Multiconfiguration Calculations
Natural Orbitals and Targeted Non-Orthogonal Orbital Sets for Atomic Hyperfine Structure Multiconfiguration Calculations Open
Hyperfine structure constants have many applications, but are often hard to calculate accurately due to large and canceling contributions from different terms of the hyperfine interaction operator, and also from different closed and spheri…
View article: Accurate and experimentally validated transition data for Si I and Si II
Accurate and experimentally validated transition data for Si I and Si II Open
Aims . The aim of this study is to provide radiative data for neutral and singly ionised silicon, in particular for the first experimental oscillator strengths for near-infrared Si I lines. In addition, we aim to perform atomic structure c…
View article: Editorial of the Special Issue “General Relativistic Atomic Structure Program—GRASP”
Editorial of the Special Issue “General Relativistic Atomic Structure Program—GRASP” Open
The year 2022 marked the 10th anniversary not only of the ATOMS journal but also of the international collaboration on Computational Atomic Structure [...]
View article: Fine-Tuning of Atomic Energies in Relativistic Multiconfiguration Calculations
Fine-Tuning of Atomic Energies in Relativistic Multiconfiguration Calculations Open
Ab initio calculations sometimes do not reproduce the experimentally observed energy separations at a high enough accuracy. Fine-tuning of diagonal elements of the Hamiltonian matrix is a process which seeks to ensure that calculated energ…
View article: GRASP Manual for Users
GRASP Manual for Users Open
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…
View article: Extended MCDHF Calculations of Energy Levels and Transition Data for N i
Extended MCDHF Calculations of Energy Levels and Transition Data for N i Open
Accurate and extensive atomic data are essential for spectroscopic analyses of stellar atmospheres and other astronomical objects. We present energy levels, lifetimes, and transition probabilities for neutral nitrogen, the sixth most abund…
View article: Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP
Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP Open
The latest published version of GRASP (General-purpose Relativistic Atomic Structure Package), i.e., GRASP2018, retains a few suboptimal subroutines/algorithms, which reflect the limited memory and file storage of computers available in th…
View article: An Introduction to Relativistic Theory as Implemented in GRASP
An Introduction to Relativistic Theory as Implemented in GRASP Open
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-sc…
View article: Independently Optimized Orbital Sets in GRASP—The Case of Hyperfine Structure in Li I
Independently Optimized Orbital Sets in GRASP—The Case of Hyperfine Structure in Li I Open
In multiconfiguration Dirac–Hartree–Fock (MCDHF) calculations, there is a strong coupling between the localization of the orbital set and the configuration state function (CSF) expansion used to determine it. Furthermore, it is well known …
View article: Re-Evaluation of the Nuclear Magnetic Octupole Moment of 209Bi
Re-Evaluation of the Nuclear Magnetic Octupole Moment of 209Bi Open
We modified the Hfs92 code of the GRASP package in order to describe the magnetic octupole hyperfine interaction. To illustrate the utility of the modified code, we carried out state-of-the-art calculations of the electronic factors of the…
View article: Signs in isotope shifts: a perennial headache
Signs in isotope shifts: a perennial headache Open
Signs of the different contributions to the isotope shift of an atomic line are discussed in details to clarify some confusing differences between the electronic parameters calculated with RIS (Nazé et al. Comput. Phys. Commun. 184 (2013) …
View article: Large-scale Multiconfiguration Dirac–Hartree–Fock Calculations for Astrophysics: C-like Ions from O iii to Mg vii
Large-scale Multiconfiguration Dirac–Hartree–Fock Calculations for Astrophysics: C-like Ions from O iii to Mg vii Open
Large-scale multiconfiguration Dirac–Hartree–Fock calculations are provided for the n ≤ 5 states in C-like ions from O iii to Mg vii . Electron correlation effects are accounted for by using large configuration state function expansions, b…
View article: Relativistic radial electron density functions and natural orbitals from GRASP2018
Relativistic radial electron density functions and natural orbitals from GRASP2018 Open
A new module, RDENSITY, of the GRASP2018 package [1] is presented for evaluating the radial electron density function of an atomic state described by a multiconfiguration Dirac-Hartree-Fock or configuration interaction wave function in the…
View article: Benchmarking calculations of wavelengths and transition rates with spectroscopic accuracy for W xlviii through W lvi tungsten ions
Benchmarking calculations of wavelengths and transition rates with spectroscopic accuracy for W xlviii through W lvi tungsten ions Open
Atomic properties of $n=3$ levels for ${\mathrm{W}}^{47+}\ensuremath{-}{\mathrm{W}}^{55+}$ ions ($Z=74$) are systematically calculated using two different and independent methods, namely, the second-order many-body perturbation theory and …
View article: Benchmarking Multiconfiguration Dirac–Hartree–Fock Calculations for Astrophysics: Si-like Ions from Cr xi to Zn xvii
Benchmarking Multiconfiguration Dirac–Hartree–Fock Calculations for Astrophysics: Si-like Ions from Cr xi to Zn xvii Open
The multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction methods are used to provide excitation energies, lifetimes, and radiative transition data for the 604 (699, 702, 704, 704, 704, and 699) lowest le…
View article: Weak Correlation and Strong Relativistic Effects on the Hyperfine Interaction in Fluorine
Weak Correlation and Strong Relativistic Effects on the Hyperfine Interaction in Fluorine Open
In previous work devoted to {\it ab initio} calculations of hyperfine structure constants in nitrogen and fluorine atoms, we observed sizeable relativistic effects, a priori unexpected for such light systems, that can even largely dominate…
View article: Laboratory Atomic Astrophysics for near-infrared Stellar Spectroscopy
Laboratory Atomic Astrophysics for near-infrared Stellar Spectroscopy Open
Astronomical infrared observations are of increasing importance for stellar spectroscopy. The analysis of element abundance relies on high-quality observations, stellar models, and ultimately on accurate atomic data. With the growing numbe…
View article: Modelling Daily Gross Primary Productivity with Sentinel-2 Data in the Nordic Region–Comparison with Data from MODIS
Modelling Daily Gross Primary Productivity with Sentinel-2 Data in the Nordic Region–Comparison with Data from MODIS Open
The high-resolution Sentinel-2 data potentially enable the estimation of gross primary productivity (GPP) at finer spatial resolution by better capturing the spatial variation in a heterogeneous landscapes. This study investigates the pote…
View article: Extended theoretical transition data in C <scp>i</scp>–<scp>iv</scp>
Extended theoretical transition data in C <span>i</span>–<span>iv</span> Open
Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C i–iv. The Multi…
View article: Theoretical investigation of oscillator strengths and lifetimes in Ti II
Theoretical investigation of oscillator strengths and lifetimes in Ti II Open
Aims. Accurate atomic data for Ti II are essential for abundance analyses in astronomical objects. The aim of this work is to provide accurate and extensive results of oscillator strengths and lifetimes for Ti II . Methods. The multiconfig…
View article: Natural orbitals in multiconfiguration calculations of hyperfine-structure parameters
Natural orbitals in multiconfiguration calculations of hyperfine-structure parameters Open
We are reinvestigating the hyperfine structure of sodium using a fully\nrelativistic multiconfiguration approach. In the fully relativistic approach,\nthe computational strategy somewhat differs from the original nonrelativistic\ncounterpa…
View article: Multiconfiguration Dirac-Hartree-Fock calculations of Landé<i>g</i>-factors for ions of astrophysical interest: B II, C I−IV, Al I−II, Si I−IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II
Multiconfiguration Dirac-Hartree-Fock calculations of Landé<i>g</i>-factors for ions of astrophysical interest: B II, C I−IV, Al I−II, Si I−IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II Open
Aims. The Landé g -factor is an important parameter in astrophysical spectropolarimetry, used to characterize the response of a line to a given value of the magnetic field. The purpose of this paper is to present accurate Landé g -factors …
View article: Theoretical studies of energy levels and transition data for Zr III
Theoretical studies of energy levels and transition data for Zr III Open
Aims. We seek to present accurate and extensive transition data for the Zr III ion. These data are useful in many astrophysical applications. Methods. We used the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interac…
View article: Benchmarking calculations with spectroscopic accuracy of excitation energies and wavelengths in sulfur-like tungsten
Benchmarking calculations with spectroscopic accuracy of excitation energies and wavelengths in sulfur-like tungsten Open
Atomic properties of S-like W are evaluated through a state-of-the-art\nmethod, namely, the multi-configuration Dirac-Hartree-Fock (MCDHF) method\ncombined with the relativistic configuration interaction (RCI) approach. The\nlevel energies…