scholarly journals Successes and Difficulties in Calculating Atomic Oscillator Strengths and Transition Rates

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 77 ◽  
Author(s):  
Alan Hibbert
Keyword(s):  
Interstellar Medium ◽  
Ab Initio ◽  
Atomic Structure ◽  
Plasma Diagnostics ◽  
Calculated Data ◽  
Stellar Atmospheres ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Transition Rates ◽  
Laboratory Measurements

There is an on-going need for accurate oscillator strengths to be used in astrophysical applications, particularly in plasma diagnostics and in the modelling of stellar atmospheres and the interstellar medium. There are several databases in regular use which contain some of the required data, although often insufficiently complete, and sometimes not sufficiently accurate. In addition, several atomic structure packages are available through the literature, or from their individual authors, which would allow further calculations to be undertaken. Laboratory measurements provide an important check on the accuracy of calculated data, and the combined efforts of theorists and experimentalists have succeeded in providing data of an accuracy sufficient for some astrophysical applications. However, the insufficiency or inadequacy of atomic data is a continuing problem. We discuss in the context of appropriate examples some of the principal steps which researchers have taken to calculate accurate oscillator strengths, including both ab initio results and also various extrapolation processes which attempt to improve such results. We also present some examples of the main causes of difficulty in such calculations, particularly for complex (many-electron) ions, and indicate ways in which the difficulties might be overcome.

scholarly journals DIVISION B COMMISSION 14 WORKING GROUP: ATOMIC DATA

2015 ◽  
Vol 11 (T29A) ◽  
pp. 103-119
Author(s):  
Gillian Nave ◽  
Sultana Nahar ◽  
Gang Zhao
Keyword(s):  
Energy Level ◽  
Working Group ◽  
Theoretical Calculations ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Laboratory Measurements ◽  
Alphabetical Order ◽  
Reference Number ◽  
Internet Databases

This report summarizes laboratory measurements of atomic wavelengths, energy levels, hyperfine and isotope structure, energy level lifetimes, and oscillator strengths. Theoretical calculations of lifetimes and oscillator strengths are also included. The bibliography is limited to species of astrophysical interest. Compilations of atomic data and internet databases are also included. Papers are listed in the bibliography in alphabetical order, with a reference number in the text.

scholarly journals The FUSE Mission: Atomic Data Needs in the 900–1200 Å Spectral Region

2002 ◽  
Vol 12 ◽  
pp. 79-81
Author(s):  
Kenneth R. Sembach
Keyword(s):  
High Resolution ◽  
Solar System ◽  
Interstellar Medium ◽  
Absorption Line ◽  
Ground State ◽  
Spectral Region ◽  
Theoretical Calculations ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Far Ultraviolet

AbstractThe Far Ultraviolet Spectroscopic Explorer (FUSE) is presently producing high resolution (R ∼ 20,000) absorption-line spectra of astronomical objects ranging from Solar System planets to quasars. The 900-1200 Å spectral region observed by FUSE is exceedingly rich in atomic and molecular transitions arising out of the ground state. It is already clear from early FUSE observations that the atomic data (e.g., oscillator strengths) for some transitions are considerably different than those predicted by theoretical calculations. I briefly describe the most pressing oscillator strength needs in this wavelength range for studies of the interstellar medium.

Allowed and forbidden transition rates and corresponding wavelengths for Si-like Au ion (Au65+) by relativistic configuration interaction method

2018 ◽  
Vol 96 (10) ◽  
pp. 1116-1137
Author(s):  
S.M. Hamasha ◽  
A. Almashaqba
Keyword(s):  
Configuration Interaction ◽  
Energy Levels ◽  
Theoretical Data ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Transition Rates ◽  
Interaction Method ◽  
Configuration Interaction Method ◽  
Relativistic Configuration ◽  
Relativistic Configuration Interaction

Large-scale atomic calculations are carried out to produce data of atomic structure and transitions rates for Si-like Au ion (Au65+). Generated atomic data are essential for modeling of M-shell spectra of gold ions in Au plasma, and fusion research. Energy levels are calculated by applying two methods: the relativistic configuration interaction method (RCI) of the flexible atomic code (FAC) and the multi-reference many body perturbation theory method (MR-MBPT). Energy levels, oscillator strengths, and transition rates are calculated for transitions between excited and ground states from n = 3l to n′l′, where n′ = 4, 5, 6, and 7; and l and l′ are the proper angular momenta of shells n and n′, respectively. The electric dipole (E1), electric quadrupole (E2), electric octupole (E3), magnetic dipole (M1), magnetic quadrupole (M2), and magnetic octupole (M3) transitions are all considered in the calculations. Correlation effects, relativistic effects, and QED effects are also included in the calculations. The two methods yield comparable values of energy levels. Data of energy levels of low-lying states and data for inner shell transitions reported in this study demonstrate good agreement with published experimental and theoretical data.

scholarly journals Electric dipole transitions between low-lying levels in doubly ionized krypton, xenon, and radon

2018 ◽  
Vol 96 (6) ◽  
pp. 664-671 ◽  
Author(s):  
Selda Eser ◽  
Leyla Özdemir
Keyword(s):  
Atomic Structure ◽  
Electric Dipole ◽  
Relativistic Effects ◽  
General Purpose ◽  
Oscillator Strengths ◽  
Transition Rates ◽  
Correlation Effects ◽  
Core Correlation ◽  
Line Strengths

Using the general-purpose relativistic atomic structure package (GRASP) based on a fully relativistic multiconfiguration Dirac–Fock (MCDF) method, the transition parameters, such as transition rates (probabilities), oscillator strengths, and line strengths for the electric dipole transitions between low-lying levels are evaluated for doubly ionized krypton, xenon, and radon. Breit interactions for relativistic effects and quantum electrodynamical (QED) contributions besides valence and valence–core correlation effects are taken into account in calculations. We compare the results obtained with the available data in the literature and discuss them, when possible.

Ab Initio Determination of Atomic Structure and Stark Broadening Parameters: Pb IV and Recent Results

2011 ◽  
Vol 20 (4) ◽  
Author(s):  
R. Hamdi ◽  
N. Ben Nessib ◽  
M. S. Dimitrijević ◽  
S. Sahal-Bréchot
Keyword(s):  
Ab Initio ◽  
Atomic Structure ◽  
Energy Levels ◽  
Relativistic Effects ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Perturbation Approach ◽  
Stark Broadening ◽  
Relativistic Approach

AbstractWe present a review of our previous ab initio calculations of Stark broadening parameters using semi-classical perturbation method for the calculation of Stark widths and shifts, and the SUPERSTRUCURE (SST) code for the determination of atomic structure. SST code takes into account the configuration interactions and relativistic effects. New results are also presented for some spectral lines of Pb IV. Energy levels and oscillator strengths are calculated using Hartree-Fock relativistic approach, and the Stark broadening parameters are determined using a semiclassical perturbation approach.

Relativistic many-body calculations of excitation energies and transition rates from core-excited states in silverlike ions

2009 ◽  
Vol 87 (1) ◽  
pp. 83-94 ◽  
Author(s):  
U I Safronova ◽  
A S Safronova
Keyword(s):  
Energy Levels ◽  
Second Order ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Transition Rates ◽  
Matrix Elements ◽  
Coupling Coefficients ◽  
Many Body ◽  
Excitation Energies ◽  
Radiation Spectra

Energies of [Kr]4d94f2, [Kr]4d94f5l, and [Kr]4d95l5l′ states (with l = s, p, d, f) for Ag-like ions with Z = 50–100 are evaluated to second order in relativistic many-body perturbation theory (RMBPT) starting from a Pd-like Dirac–Fock potential ([Kr]4d10). Second-order Coulomb and Breit–Coulomb interactions are included. Correction for the frequency dependence of the Breit interaction is taken into account in lowest order. The Lamb-shift correction to energies is also included in lowest order. Intrinsic particle–particle–hole contributions to energies are found to be 20–30% of the sum of the one- and two-body contributions. Transition rates and line strengths are calculated for the 4d–4f and 4d–5l electric-dipole (E1) transitions in Ag-like ions with nuclear charge Z = 50–100. RMBPT including the Breit interaction is used to evaluate retarded E1 matrix elements in length and velocity forms. First-order RMBPT is used to obtain intermediate coupling coefficients and second-order RMBPT is used to calculate transition matrix elements. A detailed discussion of the various contributions to the dipole matrix elements and energy levels is given for silverlike tungsten (Z = 74). The transition energies included in the calculation of oscillator strengths and transition rates are from second-order RMBPT. Trends of the transition rates as functions of Z are illustrated graphically for selected transitions. Additionally, we perform calculations of energies and transition rates for Ag-like W by the Hartree–Fock relativistic method (Cowan code) and the Multiconfiguration Relativistic Hebrew University Lawrence Atomic Code (HULLAC code) to compare with results from the RMBPT code. These atomic data are important in modeling of N-shell radiation spectra of heavy ions generated in various collision as well as plasma experiments. The tungsten data are particularly important for fusion application.PACS Nos.: 31.15.A–, 31.15.ag, 31.15.am, 31.15.aj

Energy levels, oscillator strengths, radiative decay rates, and fine structure collision strengths for Kr VII lines

2013 ◽  
Vol 91 (7) ◽  
pp. 554-559 ◽  
Author(s):  
Liang Liang ◽  
Wen-jing Gao ◽  
Chao Zhou
Keyword(s):  
Fine Structure ◽  
Structure Data ◽  
Atomic Structure ◽  
Radiative Decay ◽  
Energy Levels ◽  
Decay Rates ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Distorted Wave ◽  
Theoretical Results

Energy levels, line strengths, oscillator strengths, radiative decay rates and fine structure collision strengths are presented for six-times ionized krypton (Kr VII). The atomic data are calculated with the AUTOSTRUCTURE code, where relativistic corrections are introduced according to the Breit–Pauli distorted wave approach. We present calculations of atomic data for 40 fine-structure levels generated from nine configurations ((1s22s22p63s23p63d10)4s2, 4lnl′, n = 4, 5; l = 0, 1; and l′ ≤ 3) of the Zn-like Kr ion. Fine structure collision strengths for transitions from the ground and the first four excited levels are presented at six electron energies: 8, 15, 30, 45, 60, and 80 Ryd. Our atomic structure data are compared with the available experimental and theoretical results.

Systematic calculations of energy levels and transitions rates in Mo XXVIII

2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei
Keyword(s):  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Data Sets ◽  
Electron Systems ◽  
Excitation Energies ◽  
Experimental Values ◽  
Qed Effects ◽  
Hyperfine Structures ◽  
Good Agreement

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.

scholarly journals Extended theoretical transition data in C i–iv

2021 ◽  
Vol 502 (3) ◽  
pp. 3780-3799
Author(s):  
W Li ◽  
A M Amarsi ◽  
A Papoulia ◽  
J Ekman ◽  
P Jönsson
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Internal Validation ◽  
Hartree Fock ◽  
Relativistic Configuration ◽  
The Difference ◽  
The One ◽  
Relative Differences

ABSTRACT 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 Multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods were used in this work. To improve the quality of the wavefunctions and reduce the relative differences between length and velocity forms for transition data involving high Rydberg states, alternative computational strategies were employed by imposing restrictions on the electron substitutions when constructing the orbital basis for each atom and ion. Transition data, for example, weighted oscillator strengths and transition probabilities, are given for radiative electric dipole (E1) transitions involving levels up to 1s22s22p6s for C i, up to 1s22s27f for C ii, up to 1s22s7f for C iii, and up to 1s28g for C iv. Using the difference between the transition rates in length and velocity gauges as an internal validation, the average uncertainties of all presented E1 transitions are estimated to be 8.05 per cent, 7.20 per cent, 1.77 per cent, and 0.28 per cent, respectively, for C i–iv. Extensive comparisons with available experimental and theoretical results are performed and good agreement is observed for most of the transitions. In addition, the C i data were employed in a re-analysis of the solar carbon abundance. The new transition data give a line-by-line dispersion similar to the one obtained when using transition data that are typically used in stellar spectroscopic applications today.

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