SYSTEMATIC CALCULATIONS OF ENERGY LEVELS AND TRANSITION RATES OF C-LIKE IONS WITH Z = 13-36

Jönsson

Ekman

et al. 2017

ApJS

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Employing two state-of-the-art methods, multiconfiguration Dirac-Hartree-Fock and second-order many-body perturbation theory, the excitation energies and lifetimes for the lowest 200 states of the 2s 2 2p 4 , 2s2p 5 , 2p 6 , 2s 2 2p 3 3s, 2s 2 2p 3 3p, 2s 2 2p 3 3d, 2s2p 4 3s, 2s2p 4 3p, and 2s2p 4 3d configurations, and multipole (electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2)) transition rates, line strengths, and oscillator strengths among these states are calculated for each O-like ion from Cr XVII to Zn XXIII. Our two data sets are compared with the NIST and CHIANTI compiled values, and previous calculations. The data are accurate enough for identification and deblending of new emission lines from the sun and other astrophysical sources. The amount of data of high accuracy is significantly increased for the n = 3 states of several O-like ions of astrophysics interest, where experimental data are very scarce.

Section: Mbptmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Extended Calculations of Spectroscopic Data: Energy Levels, Lifetimes, and Transition Rates for O-like Ions from Cr xvii to Zn xxiii

Jönsson

Ekman

et al. 2017

ApJS

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“…The second-order MBPT approach (Lindgren 1974;Safronova et al 1996), implemented by Gu (2005Gu ( , 2006 in FAC has been used successfully to calculate atomic parameters with high accuracy (Gu 2007;Gu et al 2011;Wang et al 2014;Fei et al 2014;Guo et al 2015;Wang et al 2015;Si et al 2015a,b). Here we briefly describe the theory.…”

Section: Mbptmentioning

confidence: 99%

Energy levels and transition rates for helium-like ions withZ = 10–36

Guo

et al. 2016

A&A

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Aims. Helium-like ions provide an important X-ray spectral diagnostics in astrophysical and high-temperature fusion plasmas. An interpretation of the observed spectra provides information on temperature, density, and chemical compositions of the plasma. Such an analysis requires information for a wide range of atomic parameters, including energy levels and transition rates. Our aim is to provide a set of accurate energy levels and transition rates for helium-like ions with Z = 10-36. Methods. The second-order many-body perturbation theory (MBPT) was adopted in this paper. To support our MBPT results, we performed an independent calculation using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method. Results. We provide accurate energies for the lowest singly excited 70 levels among 1snl (n ≤ 6, l ≤ (n − 1)) configurations and the lowest doubly excited 250 levels arising from the K-vacancy 2ln l (n ≤ 6, l ≤ (n − 1)) configurations of helium-like ions with Z = 10−36. Wavelengths, transition rates, oscillator strengths, and line strengths are calculated for the E1, M1, E2, and M2 transitions among these levels. The radiative lifetimes are reported for all the calculated levels. Conclusions. Our MBPT results for singly excited n ≤ 2 levels show excellent agreement with other elaborate calculations, while those for singly excited n ≥ 3 and doubly excited levels show significant improvements over previous theoretical results. Our results will be very helpful for astrophysical line identification and plasma diagnostics.

“…A significant improvement in accuracy was achieved in the MBPT calculations compared with the results of the RCI method implemented in the FAC code, for example, uncertainties of wavelengths (Gu 2007) were determined to be a few mÅ through extensive comparison with the measurements of Chen et al (2007). The reliability and accuracy of this method were further confirmed by other elaborate theoretical calculations (Kotochigova et al 2007(Kotochigova et al , 2010Ekman et al 2014;Wang et al 2014) and very recent measurements (Gu et al 2011) in the EUV region. The present work has significantly increased the amount of available data for Be-like ions.…”

Section: Comparisonsmentioning

confidence: 70%

“…The analysis of these lines requires knowledge of a large number of atomic levels and transition probabilities, which are necessary to identify spectral lines, produce synthetic spectra, and carry out plasma diagnostics (Kallman & Palmeri 2007;Del Zanna & Woods 2013). With this in mind, we have carried out systematic calculations for energies and radiative transition properties in C-like ions (Wang et al 2014). This paper presents our work for Be-like ions with a nuclear charge number Z = 10-30.…”

Section: Introductionmentioning

confidence: 99%

SYSTEMATIC CALCULATIONS OF ENERGY LEVELS AND TRANSITION RATES OF BE-LIKE IONS WITH Z = 10–30 USING A COMBINED CONFIGURATION INTERACTION AND MANY-BODY PERTURBATION THEORY APPROACH

Guo

Liu

et al. 2015

ApJS

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We report calculations of energy levels and radiative rates for transitions among the lowest 116 fine-structure levels arising from the ⩽ n 5 configurations in Be-like ions with Z = 10-30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 116 levels have been calculated using the combined configuration interaction and many-body perturbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modeling and diagnostics of astrophysical and fusion plasmas.