In this theoretical study, we aim to investigate atomic properties of As-like ions: Se II, Br III, Kr IV, Rb V, and Sr VI. The multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018, are used in the present work. In the RCI calculations the transverse-photon (Breit) interaction, the vacuum polarization, and the self-energy corrections are included. By employing MCDHF method, we computed the lowest energy levels of the 4s4p 4 , 4s 2 4p 2 {4d; 5d; 5s; 6s} even and of the 4s 2 4p 3 , 4s 2 4p 2 {5p; 6p; 4f}, 4s4p 3 4d odd configurations. Accuracy of energy levels are evaluated by comparing it with the National Institute of Standards and Technology Atomic Spectra Database (NIST ASD or database) recommended values and with various methods. We calculated properties of electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) type transitions and investigated it's accuracy. We evaluated the accuracy of data, using combination of new methodology, presented in recent works.

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.

We aim to investigate atomic properties of Sb-like sequence: Sb I, Te II, I III, Xe IV, and Cs V. The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018, are used in the present work. The lowest energy levels of the 5s25p3, 5s5p4, 5p5, 5s5p35d, and 5s25p2{6s, 7s, 6p, 7p, 5d, 6d, 4f} configurations and electric dipole, magnetic dipole, and electric quadrupole transitions between states of these configurations are computed. Accuracy of energy levels are evaluated by comparing it with the National Institute of Standards and Technology Atomic Spectra Database recommended values and with other methods. Accuracy of transitions data are investigated using quantitative and qualitative evaluation method.& COPY; 2023 Elsevier Inc. All rights reserved.

The multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods were used to compute excitation energies and transition data for the 147 lowest states of the even 3s(3)p(4), 3s(2)3p2(3)d, 3p(4)3d, 3s(3)p(2)3d(2) configurations and for the 124 lowest states of the odd 3s23p3, 3p5, 3s3p33d, 3s(2)3p(3)d2, 3p(3)3d(2) configurations for the P-like ions: As XIX, Kr XXII, Sr XXIV, Zr XXVI, Mo XXVIII, and W LX. E1 transition rates and weighted oscillator strengths among these states are given. Valence-valence, core-valence and core-core electron correlation effects are included. Computed excitation energies and transition data are compared with the NIST recommended values and experimental or theoretical results of other authors. All calculations were performed using the general relativistic atomic structure package GRASP2018. (C) 2021 Elsevier Inc. All rights reserved.

The multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction methods are used to provide excitation energies, lifetimes, and radiative transition data for the 604 (699, 702, 704, 704, 704, and 699) lowest levels of the 3s 23p 2, 3s3p 3, 3s 23p3d, 3p 4, 3s3p 23d, 3s 23d 2, 3p 33d, 3s3p3d 2, 3s3d 3, 3p3d 3, 3p 23d 2, 3s 23p4s, 3s 23p4p, 3s 23p4d, 3s 23p4f, 3s3p 24s, 3s3p 24p, 3s3p 24d, 3s3p 24f, 3s 23d4s, 3s 23d4p, 3p 34s, 3p 34p, 3s3p3d4s, 3s 23p5s, and 3s 23p5p configurations in Cr xi, (Mn xii, Fe xiii, Co xiv, Ni xv, Cu xvi, and Zn xvii). Previous line identifications of Fe xiii and Ni xv in the EUV and X-ray wavelength ranges are reviewed by comprehensively comparing the MCDHF theoretical results with available experimental data. Many recent identifications of Fe xiii and Ni xv lines are confirmed, and several new identifications for these two ions are proposed. A consistent atomic data set with spectroscopic accuracy is provided for the lowest hundreds of levels for Si-like ions of iron-group elements of astrophysical interest, for which experimental values are scarce. The uncertainty estimation method suggested by Kramida, applied to the comparison of the length and velocity line strength values, is used for ranking the transition data. The correlation of the latter with the gauge dependency patterns of the line strengths is investigated.

Aims. The aim of this work is to present accurate and extensive results of energy spectra and transition data for the S II, Cl III, and Ar IV ions. These data are useful for understanding and probing physical processes and conditions in various types of astrophysical plasmas.Methods. The multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2K, are used in the present work. In the RCI calculations the transverse-photon (Breit) interaction, the vacuum polarization, and the self-energy corrections are included.Results. Energy spectra are presented comprising the 134, 87, and 103 lowest states in S II, Cl III, and Ar IV, respectively. Energy levels are in very good agreement with NIST database recommended values and associated with smaller uncertainties than energies from other theoretical computations. Electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition data are computed between the above states together with the corresponding lifetimes. Based on internal validation, transition rates for the majority of the stronger transitions are estimated to have uncertainties of less than 3%.

Aims.The Landég-factor is an important parameter in astrophysical spectropolarimetry, used to characterize the response of a line to a given value of the magnetic field. The purpose of this paper is to present accurate Landég-factors for states in B II, C I−IV, Al I−II, Si I−IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II.Methods.The multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2K, are employed in the present work to compute the Landég-factors for states in B II, C I−IV, Al I−II, Si I−IV, P II, S II, Cl III, Ar IV, Ca I, Ti II, Zr III, and Sn II. The accuracy of the wave functions for the states, and thus the accuracy of the resulting Landég-factors, is evaluated by comparing the computed excitation energies and energy separations with the National Institute of Standards and Technology (NIST) recommended data.Results.All excitation energies are in very good agreement with the NIST values except for Ti II, which has an average difference of 1.06%. The average uncertainty of the energy separations is well below 1% except for the even states of Al I; odd states of Si I, Ca I, Ti II, Zr III; and even states of Sn II for which the relative differences range between 1% and 2%. Comparisons of the computed Landég-factors are made with available NIST data and experimental values. Analysing theLS-composition of the wave functions, we quantify the departures fromLS-coupling and summarize the states for which there is a difference of more than 10% between the computed Landég-factor and the Landég-factor in pureLS-coupling. Finally, we compare the computed Landég-factors with values from the Kurucz database.

Using the multiconfiguration Dirac–Hartree–Fock and the relativistic configuration interaction methods, a consistent set of transition energies and radiative transition data for the lowest 546 (623, 701, and 745) states of the , , , , , , , , , , , , , , , and configurations in Mn xi (Fe xii, Co xiii, and Ni xiv) is provided. The comparison between calculated excitation energies for the n = 4 states and available experimental values for Fe xii indicate that the calculations are highly accurate, with uncertainties of only a few hundred cm−1. Lines from these states are prominent in the soft X-rays. With the present calculations, several recent new identifications are confirmed. Other identifications involving levels in Fe xii that were found to be questionable are discussed and a few new assignments are recommended. As some n = 4 states of the other ions also show large discrepancies between experimental and calculated energies, we reassess their identification. The present study provides highly accurate atomic data for the n = 4 states of P-like ions of astrophysical interest, for which experimental data are scarce.

In this work, we continue large-scale ab initio computations for single ionized lanthanides. Extended atomic calculations for the set of ions from Pr ii ( Z = 59) to Gd ii ( Z = 64) have been performed in our previous work. In this study, ions from Tb ii ( Z = 65) to Yb ii ( Z = 70) are analyzed. By employing the same multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods that are implemented in the general-purpose relativistic atomic structure package GRASP2018, the energy levels and transition data of electric dipole (E1) transitions are computed. These computations are based on the strategies (with small variations) of Paper I. Accuracy of data is evaluated by comparing the computed energy levels with the data provided by the National Institute of Standards and Technology (NIST) database and with data from various methods. We obtain the average accuracy in the energy level compared with the NIST database: 6%, 5%, 4%, 5%, 3%, and 3% for Tb ii , Dy ii , Ho ii , Er ii , Tm ii , and Yb ii , respectively. We also provide extensive comparison of transition probabilities and wavelengths. Our results reach the average accuracy of transition wavelengths: 9%, 9%, 9%, 3%, 4%, and 11% for Tb ii , Dy ii , Ho ii , Er ii , Tm ii , and Yb ii , respectively.

Abstract Coalescence of binary neutron stars gives rise to kilonova, thermal emission powered by radioactive decays of newly synthesized r-process nuclei. Observational properties of kilonova are largely affected by bound-bound opacities of r-process elements. It is, thus, important to understand atomic properties of heavy elements to link the observed signals with nucleosynthesis of neutron star mergers. In this paper, we introduce the latest status of kilonova modeling by focusing on the aspects of atomic physics. We perform systematic atomic structure calculations of r-process elements to understand element-to-element variation in the opacities. We demonstrate that the properties of the atomic structure of heavy elements are imprinted in the opacities of the neutron star merger ejecta and consequently in the kilonova light curves and spectra. Using this latest opacity dataset, we briefly discuss implications for GW170817, expected diversity of kilonova emission, and prospects for element identification in kilonova spectra.

Synopsis Observations of a kilonova associated with GW170817 provide a unique opportunity to study heavy element synthesis in the universe. However, the atomic data of r-process elements are not yet complete enough to decipher the light curves and spectral features of kilonovae. We performed extended atomic calculations for singly ionized elements with Z = 59 – 64, by employing GRASP2K package. These computations are based on strategies of Nd II published in [1]. Accuracy of data is evaluated by comparing computed energy levels with the NIST database and other authors.

The main aim of this paper is to present accurate energy levels of the ground [Xe]4f^12 and first excited [Xe]4f^115d configurations of Er^2+. The energy level structure of the Er^2+ ion was computed using the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction (RCI) methods, as implemented in the GRASP2018 program package. The Breit interaction, self-energy and vacuum polarization corrections were included in the RCI computations. The zero-first-order approach was used in the computations. Energy levels with the identification in LS coupling for all (399) states belonging to the [Xe]4f^12 and [Xe]4f^115d configurations are presented. Electric dipole (E1) transition data between the levels of these two configurations are computed. The accuracy of the these data are evaluated by studying the behaviour of the transition rates as functions of the gauge parameter as well as by evaluating the cancellation factors. The core electron correlations were studied using different strategies. Root-mean-square deviations obtained in this study for states of the ground and excited configurations from the available experimental or semi-empirical data are 649 cm^-1, and 747 cm^-1, respectively.

Astronomical spectroscopy has recently expanded into the near-infrared (nIR) wavelength region, raising the demands on atomic transition data. The interpretation of the observed spectra largely relies on theoretical results, and progress towards the production of accurate theoretical data must continuously be made. Spectrum calculations that target multiple atomic states at the same time are by no means trivial. Further, numerous atomic systems involve Rydberg series, which are associated with additional difficulties. In this work, we demonstrate how the challenges in the computations of Rydberg series can be handled in large-scale multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction (RCI) calculations. By paying special attention to the construction of the radial orbital basis that builds the atomic state functions, transition data that are weakly sensitive to the choice of gauge can be obtained. Additionally, we show that the Babushkin gauge should not always be considered as the preferred gauge, and that, in the computations of transition data involving Rydberg series, the Coulomb gauge could be more appropriate for the analysis of astrophysical spectra. To illustrate the above, results from computations of transitions involving Rydberg series in the astrophysically important C IV and C III ions are presented and analyzed.

Aims. The main goal of this paper is to present accurate and extensive transition data for the P II ion. These data are useful in various astrophysical applications. Methods. The multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2K, were used in the present work. In the RCI calculations the transverse-photon (Breit) interaction, the vacuum polarization, and the self-energy corrections were included. Results. Energy spectra are presented for 48 even states of the 3s23p2, 3s23p{4p, 4f, 5p, 5f, 6p}, 3s3p23d configurations, and for 58 odd states of the 3s3p3, 3s23p{3d, 4s, 4d, 5s, 5d, 6s} configurations in the P II ion. Electric dipole (E1) transition data are computed between these states along with the corresponding lifetimes. The average uncertainty of the computed transition energies is between five and ten times smaller than the uncertainties from previous calculations. The computed lifetimes for the 3s23p4s3Po states are within the error bars of the most current experimental values.

The coalescence of a binary neutron star gives rise to electromagnetic emission, known as a kilonova, that is powered by radioactive decays of r-process nuclei. Observations of a kilonova associated with GW170817 provide a unique opportunity to study heavy element synthesis in the universe. However, the atomic data of r-process elements are not yet complete enough to decipher the light curves and spectral features of kilonovae. In this paper, we perform extended atomic calculations of neodymium (Nd, Z = 60) to study the impact of the accuracy in atomic calculations on astrophysical opacities. By employing multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, we calculate the energy levels and transition data of electric dipole transitions for Nd II, NdIII, and Nd IV ions. Compared with previous calculations, our new results provide better agreement with the experimental data. The energy level accuracies achieved in the present work are 10%, 3%, and 11% for Nd II, NdIII, and Nd IV, respectively, compared to the NIST database. We confirm that the overall properties of the opacity are not significantly affected by the accuracies of the atomic calculations. The impact on the Planck mean opacity is up to a factor of 1.5, which affects the timescale of kilonovae by at most 20%. However, we find that the wavelength-dependent features in the opacity are affected by the accuracies of the calculations. We emphasize that accurate atomic calculations, in particular for low-lying energy levels, are important to provide predictions of kilonova light curves and spectra.

The multiconfiguration Dirac-Hartree-Fock method is employed to calculate the continuum electron wave functions, which are then used to estimate their contribution to the atomic electric dipole moment (EDM) of 129Xe. The EDM arises from (P,T)-odd electron-nucleon tensor-pseudotensor and pseudoscalar-scalar interactions, the nuclear Schiff moment, the interaction of the electron electric dipole moment with nuclear magnetic moments, and atomic electric dipole matrix elements. In addition to being estimated in the continuum states, all of these interactions are also estimated in the ground state, as well as in the Rydberg states of 129Xe. Calculations of one-electron atomic orbitals include the interelectronic interactions, through valence and core-valence electron correlation effects. The contribution to the EDM from continuum states is found to be of the same order of magnitude as the contribution from discrete states.

Ejected material from neutron star mergers give rise to electromagnetic emission powered by radioactive decays of r-process nuclei, which is so called kilonova or macronova. While properties of the emission are largely affected by opacities in the ejected material, available atomic data for r-process elements are still limited. We perform atomic structure calculations for r-process elements: Se (Z=34), Ru (Z=44), Te (Z=52), Ba (Z=56), Nd (Z=60), and Er (Z=68). We confirm that the opacities from bound-bound transitions of open f-shell, Lanthanide elements (Nd and Er) are higher than those of the other elements over a wide wavelength range. The opacities of open s-shell (Ba), p-shell (Se and Te), and d-shell (Ru) elements are lower than those of open f-shell elements and their transitions are concentrated in the ultraviolet wavelengths. We show that the optical brightness can be different by >2 mag depending on the element abundances in the ejecta such that post-merger, Lanthanide-free ejecta produce brighter and bluer optical emission. Such blue emission from post-merger ejecta can be observed from the polar directions if the mass of the preceding dynamical ejecta in these regions is small. For the ejecta mass of 0.01 Msun, observed magnitudes of the blue emission will reach 21.0 mag (100 Mpc) and 22.5 mag (200 Mpc) in g and r bands within a few days after the merger, which are detectable with 1m or 2m-class telescopes.

The fully relativistic multiconfiguration Dirac–Hartree–Fock method is used to compute excitation energies and lifetimes for the 143 lowest states of the , 3s3p4, , 3s3p33d, 3p5, configurations in P-like ions from Cr x to Zn xvi. Multipole (E1, M1, E2, M2) transition rates, line strengths, oscillator strengths, and branching fractions among these states are also given. Valence–valence and core–valence electron correlation effects are systematically accounted for using large basis function expansions. Computed excitation energies are compared with the NIST ASD and CHIANTI compiled values and previous calculations. The mean average absolute difference, removing obvious outliers, between computed and observed energies for the 41 lowest identified levels in Fe xii, is only 0.057%, implying that the computed energies are accurate enough to aid identification of new emission lines from the Sun and other astrophysical sources. The amount of energy and transition data of high accuracy are significantly increased for several P-like ions of astrophysics interest, where experimental data are still very scarce.