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In this paper, we present an ab initio theoretical calculation of the atomic parameters, including energy levels, wavelengths, lifetimes, and transition parameters, associated with the 1 s 22 snl and 1 s 22 pnl (n = 2–4, l ≤ n −1) configurations of Be-like sequence: Os LXXIII, Ir LXXIV, Pt LXXV, and Au LXXVI. Our analysis is based on the relativistic wavefunctions derived from the multi-configuration Dirac–Fock (MCDF) method, which are implemented in the relativistic atomic structure package GRASP2018. The correlations within the (principal quantum number) n = 10 complex are accounted for. The Breit interaction and quantum electrodynamical effects are added in the relativistic configuration interaction (RCI) calculation. Our results are compared with the existing data. The uncertainties of the dipole transition line strengths are assessed. In addition, we propose a feed forward neural network to predict the energy levels of Au LXXVI. This is a powerful machine learning tool capable of learning from existing data and predicting unknown data. The network is trained using theoretical energy levels of Os LXXIII, Ir LXXIV, and Pt LXXV obtained from the MCDF method. Our neural network exhibits average relative deviations of approximately 0.01% and 0.02% for trained and predicted energy levels, respectively, when compared to the MCDF results. This level of deviation suggests that our results are reasonably accurate. The data set presented in this study is useful for modeling fusion plasmas. • Energies and transition probabilities in Os LXXIII, Ir LXXIV, Pt LXXV, and Au LXXVI of fusion interest are calculated. • The relativistic multiconfiguration Dirac–Fock method is employed. • The neural network is employed. • The calculated data are useful for fusion research. [ABSTRACT FROM AUTHOR]

Highlights • Hyperfine structure and radiative transition of C-like Fe, Co and Ni are studied. • Electron correlation effect are investigated in detail. • Influences of Breit and QED effect on energies are studied. • The radiative spectra may provide theoretical support for experimental study. Abstract Energy levels, hyperfine structure and 2s-2p radiative transition processes of C-like Fe, Co and Ni are studied by performing multiconfiguration Dirac–Hartree–Fock method using the fully relativistic codes GRASP2K. Electron correlation effect on the energies, hyperfine structure constants and radiative transition rates are investigated in detail. Influences of Breit and quantum electrodynamics (QED) effect on energies are studied. Good agreements are found between the results in this work and experimental data. The radiative spectra of the excited states 1s22s2p3 and 1s22p4 of C-like Fe, Co and Ni may provide theoretical support for further experimental study. Since Fe, Co and Ni are important constituent part of experimental apparatus (such as EBIT), the data in this work have important application value for experimental application. [ABSTRACT FROM AUTHOR]

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The hydrogen like ion is the simplest structure of an atom, so the studying on it gives a change to test of methods using for determinating of atomic structures. It is also an occasion the studying on hydrogen like ions to understand atomic structure. For this reason, it is performed a study for hydrogen like nobelium (No101+, Z=102). It has been used both multiconfiguration Hartree-Fock, MCHF, and multiconfiguration Dirac-Fock method, MCDF, as calculating level structure of No101+. The calculations have contained some relativistic corrections and quantum electrodynamic effects. There are very few theoretical works in available literature and no experimental one for No101+. The calculated results have been interpreted in comparison with other theoretical results. [ABSTRACT FROM AUTHOR]

Multi-configuration Dirac–Fock (MCDF) calculations of energy levels, wavelengths, oscillator strengths, lifetimes, and electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2) transition rates are reported for the arsenic isoelectronic sequence Sn XVIII-Ba XXIV, W XLII. Results are presented among the 86 levels of the 4 s 2 4 p 3 , 4 s 4 p 4 , 4 p 5 , 4 s 2 4 p 2 4 d , and 4 s 4 p 3 4 d configurations in each ion. The relativistic atomic structure package GRASP2K is adopted for the calculations, in which the contributions from the correlations within the n ≤ 7 complexes, Breit interaction (BI) and quantum electrodynamics (QED) effects are taking into account. The many-body perturbation theory (MBPT) method is also employed as an independent calculation for comparison purposes, taking W XLII as an example. Calculated results are compared with data from other calculations and the observed values from the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST). Good agreements are obtained. i.e, the accuracy of our energy levels is assessed to be better than 0.6%. These accurate theoretical data should be useful for diagnostics of hot plasmas in fusion devices. [ABSTRACT FROM AUTHOR]

Energies, wavelengths, lifetimes, oscillator strengths, electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transition rates among the 42 fine structure levels belonging to the 3s23p4, 3s23p33d, and 3s3p5 configurations for S-like Fe and S-like ions with 41 ≤ Z ≤ 49 are calculated using the fully relativistic multiconfiguration Dirac-Fock (MCDF) method. In the calculations, contributions from correlations within the n = 6 complex, Breit interaction, and quantum electrodynamics effects are included. Detailed comparisons are made between the present results and the available experimental and other theoretical data. We found that our calculated energy levels generally agree within ≤0.5% with the experimentally compiled results, and the transition rates agree within ≤12% with other theoretical results for a majority of the transitions. These accurate theoretical data should be beneficial in fusion plasma research and astrophysical applications. [ABSTRACT FROM AUTHOR]

Wavelengths, transition probabilities, and oscillator strengths have been calculated for M-shell electric dipole (E1) transitions in Al-like W61+ through Cl-like W57+, with partially filled 3p subshell. The fully relativistic multiconfiguration Dirac-Fock (MCDF) method, taking quantum electrodynamical effect and Breit correction into account, was used in the calculations. Calculated energy levels of M-shell excited states in Al-like through Cl-like W ions from the method were compared with some available theoretical and experimental results, and good agreement with them was achieved. [ABSTRACT FROM AUTHOR]

Hydrogen-like ions with high Z present unique opportunities to promote the understanding of atomic structure. On the other hand, determining the atomic structure of hydrogen-like atoms provides us the test of relativistic effects as well as accurate values of the spectral characteristics required for many applications. For this reason we have calculated level energies of hydrogen like thorium (Th89+, Z = 90) with both multiconfiguration Hartree-Fock (MCHF) and multiconfiguration Dirac-Fock (MCDF) methods. These calculations have contained the Breit-Pauli relativistic corrections in MCHF calculation and quantum electrodynamics effects in MCDF calculations besides electron correlations. The wavelengths, λ, weighted oscillator strengths, gf-value, and transition probabilities, Aki, have been also represented for allowed (E1) and forbidden (E2 and M1) transitions. We have compared our results with only theoretical work results because there is no available experimental data for Th89+. [ABSTRACT FROM AUTHOR]

The fully relativistic multiconfiguration Dirac-Fock (MCDF) method is employed to calculate the excitation energies and wavelengths for nine isoelectronic sequences of tungsten ions. In calculations, electron correlations, quantum electrodynamical (QED) effect, and Breit correction are taken into account. The core-valence and valence-valence corrections are analyzed in a systematic way. The core setting was systematically studied for four cases of one electron occupying the outermost s orbital, one electron occupying the outermost p orbital, three electrons occupying the outermost p orbital, and one electron occupying the outermost d orbital. In our research, at least two calculation models are adopted for every tungsten ion. Through analyzing our results, it is found that the following three calculation models can help to get results closer to measured values: ( i) setting the closed shells as core; ( ii) taking core-valence corrections into account when there is only one valence electron; ( iii) taking valence-valence corrections into account when the number of valence electrons is not less than three. The purpose of this paper is to provide some references on configuration selection and configuration interaction in calculations for a multi-electron system of highly charged tungsten ions. [ABSTRACT FROM AUTHOR]

We have reported a relativistic multiconfiguration Dirac-Fock calculation including Breit and quantum electrodynamic contributions on the level structure of atomic actinium, Ac I (Z = 89). The computations have been carried out for the low 45 even and 60 odd-parity levels, and the electric dipole transition parameters (wavelengths, oscillator strengths and transition probabilities) for some transitions between these levels. Comparison has been also made with other results in available literature. [ABSTRACT FROM AUTHOR]

Abstract: Hyperfine induced transition rates in an external magnetic field for Be-like 47Ti were calculated based on the multiconfiguration Dirac–Fock method. It was found that the transition probability is dependent on the magnetic quantum number of the excited state, even in the weak field. The present investigation clarifies that the difference of the hyperfine induced transition rate of Be-like Ti ions between experiment [Schippers, et al., Phys. Rev. Lett. 98 (2007) 033001(4)] and theory does not result from the influence of external magnetic field. [ABSTRACT FROM AUTHOR]

The multi-configuration Dirac-Fock (MCDF) method is implemented to study doubly excited2s2p 1,3P1 resonances of the helium atom and the interference between photoionization and photoexcitation autoionization processes. In order to reproduce the total photoionization sprectra, the excited energies from the ground 1s2 1S0 state to the doubly excited 2s2p 1,3P1 states and the relevant Auger decay rates and widths are calculated in detail. Furthermore, the interference profile determined by the so-called Fano parameters q and p2 is also reproduced. Good agreement is found between the present results and other available theoretical and experimental results. This indeed shows a promising way to investigate the Fano resonances in photoionization of atoms within the MCDF scheme, although there are some discrepancies in the present calculations of the 2s2p 3P1 state. [ABSTRACT FROM AUTHOR]

A super heavy element Uub ( Z = 112) has been studied theoretically in conjunction with relativistic effects and the effects of electron correlations. The atomic structure and the oscillator strengths of low-lying levels have been calculated, and the ground states have also been determined for the singly and doubly charged ions. The influence of relativity and correlation effects to the atomic properties of such a super heavy element has been investigated in detail. The results have been compared with the properties of an element Hg. Two energy levels at wave numbers 64470 and 94392 are suggested to be of good candidates for experimental observations. [ABSTRACT FROM AUTHOR]

In the last few years, the Ratip package has been found useful for studying the properties of atoms and (highly charged) ions within rather arbitrary configurations. Here, the latest extensions to this code are reviewed which help calculate several Auger and photoionization parameters, including cross sections, angular coefficients as well as correlation functions for the emitted electrons. In addition, a number of recent case studies on the electron spectra of resonantly excited noble gases and open-shell atoms are briefly summarized. [Copyright &y& Elsevier]

The effects of correlation and relaxation on the 2p53s 1,3P1–2p6 1S0 resonance and intercombination transitions of neutral neon have been studied systematically using the Multi-configuration Dirac–Fock (MCDF) method. Results are presented for the energies and lifetimes of the low-lying 1,3P1 levels as well as the according transition probabilities. Lifetimes for the two metastable 3P0,2 levels are obtained also from the calculation of the 3P2–1S0 magnetic-quadrupole (M2) and from the 3P0–3P1 magnetic-dipole (M1) and 3P0–3P2 electric-quadrupole (E2) transitions, respectively. Comparison is made for our theoretical results with previous computations and measurements; they are found to be in good agreement with recently evaluated data. [ABSTRACT FROM AUTHOR]

Using fully relativistic multiconfiguration Dirac–Fock (MCDF) wavefunctions in an active space approximation, we perform systematic calculations of the energies, wavelengths, and lifetimes for the lowest 143 levels belonging to the 3 p 6 3 d 6 and 3 p 5 3 d 7 configurations of Cr-like ions between Hf XLIX and Au LVI. Additionally, line strengths, oscillator strengths, and radiative rates for the electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among these levels are reported. In the calculations, the contributions from Breit interaction (BI) and quantum electrodynamics (QED) corrections to the wave functions are taken into account (the addition of the BI and QED in CI affects both the wave functions and the level energies). For some excited states, there are no other theoretical and/or experimental data to compare with to illustrate the quality of our results/assess the accuracy. A similar calculation has been performed with the Flexible Atomic Code (FAC), using W LI as an example. The results obtained in this work are compared with the data compiled in the Atomic Spectra Database (ASD) of the National Institute of Standards and Technology (NIST) and other available theoretical/experimental information. Satisfactory agreement is found between them. The energies agree within 0.8% with the experimental results, and the M1 transition rates agree within 5% with other theoretical results. The present results are more extensive than those from previous calculations and considerably expand the existing data sets for Cr-like ions. This study should be beneficial for the analysis of experimental spectra and modeling of fusion plasmas. [ABSTRACT FROM AUTHOR]