The hyperfine constants of the levels 2
p
2
P)3
s
4
P
J
, 2
p
2
P)3
p
4
P
and 2
p
2
P)3
p
4
D
, deduced by Jennerich et al. Eur. Phys. J. D
40
, 81 (2006) from the observed hyperfine structures ...of the transitions 2
p
2
P)3
s
4
P
J
2
p
2
P)3
p
4
P
and 2
p
2
P)3
s
4
P
J
2
p
2
P)3
p
4
D
recorded by saturation spectroscopy in the near-infrared, strongly disagree with the ab initio values of Jönsson et al. J. Phys. B: At. Mol. Opt. Phys.
43
, 115006 (2010). We propose a new interpretation of the recorded weak spectral lines. If the latter are indeed reinterpreted as crossover signals, a new set of experimental hyperfine constants is deduced, in very good agreement with the ab initio predictions.
In this Letter Quantum Similarity for Atoms (H–Xe) is investigated using electron densities and shape functions, looking for patterns of periodicity as in Mendeleev’s Table. An
LS-dependent ...restricted Hartree–Fock method is used to obtain the wave functions from which the electron densities are calculated. Utilizing the quantum similarity proposed by Carbó a nearest neighbour dominated similarity is retrieved, masking periodicity. Introduction of the information discrimination concept with reference to the noble gas atom of the previous row is found to reveal periodicity, with improved results when densities are replaced by shape functions throughout. This confirms recent literature on the fundamental role of the shape function as carrier of information.
Ocean acidification has emerged as a major concern in the last fifteen years and studies on the impacts of seawater acidification on marine organisms have multiplied accordingly. This review aimed at ...synthesizing the literature on the effects of seawater acidification on tropical scleractinians under laboratory-controlled conditions. We identified 141 articles (published between 1999 and 2021) and separated endpoints into 22 biological categories to identify global trends for mitigation and gaps in knowledge and research priorities for future investigators. The relative number of affected endpoints increased with pH intensity (particularly for endpoints associated to calcification and reproduction). When exposed to pH 7.6–7.8 (compared to higher pH), 49% of endpoints were affected. The diversity in experimental designs prevented deciphering the modulating role of coral life stages, genera or duration of exposure. Finally, important bias in research efforts included most experiments on adult corals (68.5%), in 27 out of 150 (18%) coral ecoregions and exclusively from shallow-waters.
•Seawater acidification experiments on tropical scleractinians are relatively recent.•Seawater acidification mainly affects calcification and reproduction capacities.•Knowledge is biased with a majority of work on adult and shallow-water corals.•Geographical bias: acidification experiments performed in only 18% of coral ecoregions.•We recommend a list of actions and priorities for future research in this field.
Ab initio multiconfiguration calculations are performed for the oscillator strengths of the λ = 4238, 4262 and 4297 Å Tc i resonance lines of astrophysical interest. Electron correlation is treated ...through multiconfiguration expansions built from elaborate correlation models, while relativistic effects are introduced in the perturbation Breit—Pauli approximation or in the multiconfiguration Dirac—Fock—Breit variational approach. The calculated gf-values are sensitively lower (≈30 per cent) than the values obtained with the pseudo-relativistic Hartree—Fock wavefunctions calculated from a parametric analysis of Tc i by Palmeri & Wyart. The inclusion of a core-polarization potential in the latter approach confirms the present ab initio results when different ionic cores are used for the different transition arrays. The strong lines of Tc i are revisited adopting this model, giving rise to a systematic reduction in the oscillator strength scale due to core polarization. The astrophysical implications are discussed.
Spectral lines from different isotopes display a small separation in energy, commonly referred to as the line isotope shift. The program RIS4 (Relativistic Isotope Shift) calculates normal and ...specific mass shift parameters as well as field shift electronic factors from relativistic multiconfiguration Dirac-Hartree-Fock wave functions. These quantities, together with available nuclear data, determine isotope-dependent energy shifts. Using a reformulation of the field shift, it is possible to study, in a model-independent way, the atomic energy shifts arising from changes in nuclear charge distributions, e.g. deformations. (C) 2018 Published by Elsevier B.V.
When the effects of the finite mass of the nucleus and the spatial nuclear charge distribution are taken into account in the Hamiltonian describing an atomic system, the isotopes of an element have ...different electronic energy levels. In the present work, we are investigating these mass and field effects in neutral barium, hoping to shed some light on the surprising observed deviation of isotope shifts from their expected behavior for odd isotopes in an analysis based on King-plots.
We use the multiconfiguration Dirac-Hartree-Fock (MCDHF) method combined with the relativistic configuration interaction approach (GRASP2K) to provide a consistent set of transition energies and ...radiative transition data for the lower n = 3 states in all Cl-like ions of astrophysical importance, from Cr VIII to Zn XIV. We also provide excitation energies calculated for Fe X using the many-body perturbation theory (MBPT, implemented within FAC). The comparison of the present MCDHF results with MBPT and with the available experimental energies indicates that the theoretical excitation energies are highly accurate, with uncertainties of only a few hundred cm(-1). Detailed comparisons for Fe X and Ni XII highlight discrepancies in the experimental energies found in the literature. Several new identifications are proposed.
•Excitation energies and wavelengths of n=3 states of the W LVII–W LXII tungsten ions are systematically investigated.•Electron correlation, Breit interaction and QED corrections to the excitation ...energies are studied in detail.
Atomic properties of n=3 states of the W56+ - W61+ ions are systematically investigated through two state-of-the-art methods, namely, the second-order many-body perturbation theory, and the multi-configuration Dirac–Hartree–Fock method combined with the relativistic configuration interaction approach. The contributions of valence-valence and core-valence electron correlations, the Breit interaction, the higher-order retardation correction beyond the Breit interaction through the transverse photon interaction, and the quantum electrodynamical corrections to the excitation energies are studied in detail. The excitation energies and wavelengths obtained with the two methods agree with each other within ≈0.01%. The present results achieve spectroscopic accuracy and provide a benchmark test for various applications and other theoretical calculations of W56+ - W61+ ions. They will assist spectroscopists in their assignment and direct identification of observed lines in complex spectra.
In this study, the sensitivity of the opacities with respect to the atomic parameters is investigated in the case of weakly charged uranium ions. In order to do this, atomic data for U II and U III ...were calculated with the pseudo-relativistic Hartree–Fock method (HFR) and then, used to determine the expansion opacities for conditions characterizing the ejecta of kilonovae that follow neutron star mergers. In particular, we studied the sensitivity of the opacity with respect to the use of atomic data obtained considering several effects as the ionic core polarization and an adjustment procedure.
Graphical abstract
In the present work, we report an investigation on the importance of using realistic partition functions in the opacity calculations of lanthanide ions whether they are moderately or lowly ionized. ...In order to do this, atomic data for various moderately charged samarium (Sm V–XI) and lowly charged neodymium (Nd II–IV) ions were calculated by the pseudo-relativistic Hartree–Fock method (HFR) and then, used to compute the expansion opacities for conditions characterizing the ejecta of kilonovae observed as a result of neutron star mergers, with a particular attention given to the partition function computations.
Graphical abstract
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