Atomic data from the Iron Project

Nahar, Sultana N.; Delahaye, F.; Pradhan, Anil K.; Zeippen, C. J.

doi:10.1051/aas:2000339

Cited by 26 publications

(22 citation statements)

References 19 publications

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“…These transitions are comparatively stronger than the corresponding E2 ones among these levels, also reported in [32]. Similar results of [18] Table F we show comparisons for a few, particularly those with larger strengths. As for M1 transitions, for these E2 also there are no discrepancies between the two calculations, except that there is a difference of about a factor of two, and our results are lower.…”

Section: Radiative Rates and Lifetimessupporting

confidence: 90%

“…There are no Tables ( ) -7 available theoretical or experimental τ data for comparison purposes, but there are no appreciable disagreements with previous theoretical results of g, available for only a few levels of Fe V. Radiative rates for the three ions have also been reported for all E1, E2 and M1 emission transitions. Earlier data for the E1 transitions are available for Fe V by [18,19]. However, in comparison to our calculations and those of others [10,20], their A-values appear to be less accurate, and so are their energy levels which differ from the measurements and our work by some 10% for many levels.…”

Section: Discussioncontrasting

confidence: 72%

“…However, the observed spectrum of Ni VII is not as rich as for the other Ti-like ions Fe V and Co VI, because many levels are missing for the 3d 4 and 3d 3 4p configurations and none has been measured for 3d 3 4s-see Table 3 or the NIST website. Additionally, the situation regarding radiative data (A-values) is even worse, particularly for Co VI and Ni VII, although some results are available for Fe V [14,[17][18][19][20]. Therefore, in this paper we calculate energy levels and A-values for three Ti-like ions, namely Fe V, Co VI and Ni VII.…”

Section: Introductionmentioning

confidence: 99%

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Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

Aggarwal

Bogdanovich

Keenan

et al. 2017

Atomic Data and Nuclear Data Tables

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a b s t r a c tEnergy levels, Landé g-factors and radiative lifetimes are reported for the lowest 182 levels of the 3d 4 , 3d 3 4s and 3d 3 4p configurations of Fe V, Co VI and Ni VII. Additionally, radiative rates (A-values) have been calculated for the E1, E2 and M1 transitions among these levels. The calculations have been performed in a quasi-relativistic approach (QR) with a very large configuration interaction (CI) wavefunction expansion, which has been found to be necessary for these ions. Our calculated energies for all ions are in excellent agreement with the available measurements, for most levels. Discrepancies among various calculations for the radiative rates of E1 transitions in Fe V are up to a factor of two for stronger transitions (f ≥ 0.1), and larger (over an order of magnitude) for weaker ones. The reasons for these discrepancies have been discussed and mainly are due to the differing amount of CI and methodologies adopted. However, there are no appreciable discrepancies in similar data for M1 and E2 transitions, or the g-factors for the levels of Fe V, the only ion for which comparisons are feasible.

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Section: Radiative Rates and Lifetimessupporting

confidence: 90%

Section: Discussioncontrasting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

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Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

Aggarwal

Bogdanovich

Keenan

et al. 2017

Atomic Data and Nuclear Data Tables

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“…The fobidden quadrupole (E2) and magnetic dipole (Ml) transitions are treated with atomic structure calculations using codes such as SUPERSTUCTURE (Eissner et al 1974). The first large-scale application of the BPRM method for a complex ion, Fe V, resulted in 3865 fine structure energy levels, compared to 179 observed, and about 1.46 million f-and A-values for dipole allowed and intercombination (El) transitions and 362 forbidden (E2,Ml) transitions (Nahar et al 2000). Table I with experiment, is shown in Fig.…”

Section: Bound-bound Transitionsmentioning

confidence: 99%

Atomic Processes in Planetary Nebulae

Nahar

2003

Symp. - Int. Astron. Union

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Abstract. A hot central star illuminating the surrounding ionized H II region usually produces very rich atomic spectra resulting from basic atomic processes: photoionization, electron-ion recombination, boundbound radiative transitions, and collisional excitation of ions. Precise diagnostics of nebular spectra depend on accurate atomic parameters for these processes. Latest developments in theoretical computations are described, especially under two international collaborations known as the Opacity Project (OP) and the Iron Project (IP), that have yielded accurate and large-scale data for photoionization cross sections, transition probabilities, and collision strengths for electron impact excitation of most astrophysically abundant ions. As an extension of the two projects, a self-consistent and unified theoretical treatment of photoionization and electron-ion recombination has been developed where both the radiative and the dielectronic recombination processes are considered in an unified manner. Results from the Ohio State atomic-astrophysics group, and from the OP and IP collaborations, are presented. A description of the electronic web-interactive database, TIPTOPBASE, with the OP and the IP data, and a compilation of recommended data for effective collision strengths, is given.

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“…The Breit-Pauli R-matrix (BPRM) method [1] is being used to calculate a large number of oscillator strengths (f -values) [2][3][4][5]. The first large scale application of the BPRM method for the radiative transitions in Fe XXIV and Fe XXV [2] showed very good agreement, within 10%, of the f -values with the most accurate theoretical calculations available.…”

Section: Introductionmentioning

confidence: 99%

Fine Structure Radiative Transitions in C Ii and C Iii Using the Breit–pauli R-Matrix Method

Nahar

2002

Atomic Data and Nuclear Data Tables

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Extensive sets of radiative transitions in C II and in C III are obtained using the relativistic Breit-Pauli R-matrix (BPRM) method. In comparison with other accurate methods that can be applied to relatively few transitions, the BPRM method enables calculations of a large number of transitions with comparable accuracy for most of them. The present work reports large-scale calculations for two important ions obtaining 127 and 206 bound fine structure energy levels, resulting in 1681 and 4202 dipole allowed and intercombination transitions for C II and C III, respectively. Detailed comparison of the BPRM results is made with those from experimental and theoretical studies, including the relativistic multiconfiguration Dirac-Fock method. INTRODUCTIONThe Breit-Pauli R-matrix (BPRM) method [1] is being used to calculate a large number of oscillator strengths (f -values) [2][3][4][5]. The first large scale application of the BPRM method for the radiative transitions in Fe XXIV and Fe XXV [2] showed very good agreement, within 10%, of the f -values with the most accurate theoretical calculations available. Most of the experimental and theoretical studies for oscillator strengths and transition probabilities (A-values) are focused on a few or a limited number of transitions, whereas various spectral diagnostic models and astrophysical applications, such as plasma opacities, require f -or A-values for a very large number of transitions. Systematic calculations for radiative processes were carried out for most astrophysically abundant atoms and ions under the Opacity Project (OP [6][7][8][9]). The datasets obtained under the OP are available electronically through a database, TOPbase [10]. The calculations under the OP were carried out in LS coupling and no relativistic effects were considered. However, fine structure transitions, rather than LS multiplets, are needed for spectral diagnostics in astrophysical and laboratory plasmas. The Breit-Pauli R-matrix method developed under the Iron Project (IP, [1]) includes relativistic effects in the Breit-Pauli approximation [1,11,12] for collisional processes. Recently, the method has been extended to enable close coupling calculations of oscillator strengths (i) including the relativistic effects and (ii) considering a large number of transitions.The present study investigates the relativistic and electron-electron correlation effects in transitions of two important light ions, C II and C III. These two ions are of particular interest in the diagnostics of a number of astrophysical objects such as in early type stars and nebulae as well as in laboratory plasmas. THEORYProvided here is a brief summary of the the basics of the Breit-Pauli R-matrix method. The method for radiative bound-bound and bound-free transitions is derived from atomic collision theory and the coupled channel or close coupling (CC) approximation [1,6]. The computational method is based on the powerful R-matrix formalism that enables efficient, accurate, and large-scale calculations of compound (bound and c...

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Atomic data from the Iron Project

Cited by 26 publications

References 19 publications

Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

Energy levels and radiative rates for transitions in Fe V, Co VI and Ni VII

Atomic Processes in Planetary Nebulae

Fine Structure Radiative Transitions in C Ii and C Iii Using the Breit–pauli R-Matrix Method

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