Accurate transition probabilities for the 2s2 1S - 2s2p 1P transition in Be I and B II

Irving, R. E.; Henderson, M.; Curtis, L. J.; Martinson, I.; Bengtsson, Peter

doi:10.1139/p99-015

Cited by 17 publications

(18 citation statements)

References 25 publications

(40 reference statements)

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“…In 1994, Ellis et al measured lifetimes of 2p3p and 2p3d levels in Be I and calculated them using the Hartree-Fock method [12] . Transition probabilities were reported for the 2s 2 1 S-2s2p 1 P o transition in Be I by Irving et al and Schnabel and Kock in 1999 and 20 0 0, respectively [13,14] .…”

Section: Introductionmentioning

confidence: 86%

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Radiative lifetimes, branching fractions, and oscillator strengths of some levels in Be I

Wang

Quinet

et al. 2018

Journal of Quantitative Spectroscopy and Radiative Transfer

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Radiative lifetimes of five levels in Be I lying in the energy range 64,506.45-71,160.52 cm −1 were measured by the time-resolved laser-induced fluorescence technique. These new data, together with previously measured radiative lifetimes and two reliable calculated lifetimes, were combined with branching fractions obtained from pseudo-relativistic Hartree-Fock calculations to deduce semi-empirical transition probabilities and oscillator strengths for 90 Be I spectral lines involving upper levels ranging from 42,565.35 to 72,251.27 cm −1 .

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Section: Introductionmentioning

confidence: 86%

“…In theoretical calculations, beryllium atom is also an attractive system because it provides interesting examples of electron correlation, core polarization, and relativistic effects [13] . In the past 70 years, there has been extensive theoretical research on transition probabilities of Be I.…”

Section: Introductionmentioning

confidence: 99%

Radiative lifetimes, branching fractions, and oscillator strengths of some levels in Be I

Wang

Quinet

et al. 2018

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…Also, the agreement between the length and velocity forms is not as good for the PCFI method as for the ordinary MCHF. [36] 1.40 ± 0.04 Schnabel and Kock [37] 1.34 ± 0.03…”

Section: The Constraint Effectmentioning

confidence: 99%

A partitioned correlation function interaction approach for describing electron correlation in atoms

Verdebout

Rynkun

Jönsson

et al. 2013

J. Phys. B: At. Mol. Opt. Phys.

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The traditional multiconfiguration Hartree-Fock (MCHF) and configuration interaction (CI) methods are based on a single orthonormal orbital basis. For atoms with many closed core shells, or complicated shell structures, a large orbital basis is needed to saturate the different electron correlation effects such as valence, core-valence and correlation within the core shells. The large orbital basis leads to massive configuration state function (CSF) expansions that are difficult to handle, even on large computer systems. We show that it is possible to relax the orthonormality restriction on the orbital basis and break down the originally very large calculations into a series of smaller calculations that can be run in parallel. Each calculation determines a partitioned correlation function (PCF) that accounts for a specific correlation effect. The PCFs are built on optimally localized orbital sets and are added to a zero-order multireference (MR) function to form a total wave function. The expansion coefficients of the PCFs are determined from a low dimensional generalized eigenvalue problem. The interaction and overlap matrices are computed using a biorthonormal transformation technique (Verdebout et al 2010 J. Phys. B: At. Mol. Phys. 43 074017). The new method, called partitioned correlation function interaction (PCFI), converges rapidly with respect to the orbital basis and gives total energies that are lower than the ones from ordinary MCHF and CI calculations. The PCFI method is also very flexible when it comes to targeting different electron correlation effects. Focusing our attention on neutral lithium, we show that by dedicating a PCF to the single excitations from the core, spin-and orbital-polarization effects can be captured very efficiently, leading to highly improved convergence patterns for hyperfine parameters compared with MCHF calculations based on a single orthogonal radial orbital basis. By collecting separately optimized PCFs to correct the MR function, the variational degrees of freedom in the relative mixing coefficients of the CSFs building the PCFs are inhibited. The constraints on the mixing coefficients lead to small off-sets in computed properties such as hyperfine structure, isotope shift and transition rates, with respect to the correct values. By (partially) deconstraining the mixing coefficients one converges to the correct limits and keeps the tremendous advantage of improved convergence rates that comes from the use of several orbital sets. Reducing ultimately each PCF to a single CSF with its own orbital basis leads to a non-orthogonal CI approach. Various perspectives of the new method are given.

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“…Computations of neutral atoms are particularly challenging, and, indeed, neutral Be 0 has been declared to be of interest as a benchmark. There are beam-foil lifetime results from early days by Martinson, Gaupp and Curtis [30] and much later ones by Irving et al [31], and they differ by some 4.5%. Since the early data point predates the development of the ANDC cascade correction technique, one would assume that the newer data point benefits from the better insight and must be better.…”

Section: Resonance Transition Ratementioning

confidence: 94%

“…So, whatever experimental value is taken for comparison, the theory-experiment mismatch is around 2%-3%, much worse than the theoretical uncertainty estimate. However, isoelectronically smoothed representations of the line strength and similar averaging procedures recounted and discussed by Irving et al [31] pass through the region of overlap of the experimental error bars for Be I. Maybe for now the experimental results should be represented by their weighted average.…”

Section: Resonance Transition Ratementioning

confidence: 99%

Critical Assessment of Theoretical Calculations of Atomic Structure and Transition Probabilities: An Experimenter’s View

Trabert

2014

Atoms

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The interpretation of atomic observations by theory and the testing of computational predictions by experiment are interactive processes. It is necessary to gain experience with "the other side" before claims of achievement can be validated and judged. The discussion covers some general problems in the field as well as many specific examples, mostly organized by isoelectronic sequence, of what level of accuracy recently has been reached or which atomic structure or level lifetime problem needs more attention.

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Accurate transition probabilities for the 2s² ¹S - 2s2p ¹P transition in Be I and B II

Cited by 17 publications

References 25 publications

Radiative lifetimes, branching fractions, and oscillator strengths of some levels in Be I

Radiative lifetimes, branching fractions, and oscillator strengths of some levels in Be I

A partitioned correlation function interaction approach for describing electron correlation in atoms

Critical Assessment of Theoretical Calculations of Atomic Structure and Transition Probabilities: An Experimenter’s View

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