Multi-configuration Dirac-Hartree-Fock (MCDHF) calculations for Zn-like sequence from Z=48 to 54

The 4s4p excitation energies and the 4s24s4pE1 transitions for zinc-like ions from Z = 48 to 54 are calculated by the multi-configuration Dirac-Hartree-Fock （MCDHF） method in this paper. The results for fine-structure energy levels, wavelengths and lifetimes between Z = 48 （Cd） and Z = 54 （Xe） are presented and compared with other theoretical and experimental results. The calculated values including core-valence correlation are found to be very similar to other theoretical and experimental values. We believe that our calculated values can guide experimentalists in identifying the fine-structure levels in their future work.

Benchmarking calculations of excitation energies and transition properties with spectroscopic accuracy of highly charged ions used for the fusion plasma and astrophysical plasma

Atomic radiative data such as excitation energies, transition wavelengths, radiative rates, and level lifetimes with high precision are the essential parameters for the abundance analysis, simulation, and diagnostics in fusion and astrophysical plasmas. In this work, we mainly focus on reviewing our two projects performed in the past decade. One is about the ions with Z■30 that are generally of astrophysical interest, and the other one is about the highly charged krypton(Z = 36)and tungsten(Z = 74) ions that are relevant in research of magnetic confinement fusion. Two different and independent methods, namely, multiconfiguration Dirac–Hartree–Fock(MCDHF) and the relativistic many-body perturbation theory(RMBPT) are usually used in our studies. As a complement/extension to our previous works for highly charged tungsten ions with open M-shell and open N-shell, we also mainly focus on presenting and discussing our complete RMBPT and MCDHF calculations for the excitation energies, wavelengths, electric dipole(E1), magnetic dipole(M1), electric quadrupole(E2), and magnetic quadrupole(M2) transition properties, and level lifetimes for the lowest 148 levels belonging to the 3l3configurations in Al-like W61+. We also summarize the uncertainties of our systematical theoretical calculations, by cross-checking/validating our datasets from our RMBPT and MCDHF calculations, and by detailed comparisons with available accurate observations and other theoretical calculations. The data are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.10569.

Effects of electron correlation and the Breit interaction on one- and two-electron one-photon transitions in double K hole states of He-like ions(10 ≤ Z ≤ 47)

The x-ray energies and transition rates associated with single and double electron radiative transitions from the double K hole state 2s2p to the 1s2s and 1s^2 configurations of 11 selected He-like ions(10 ≤ Z ≤ 47) are calculated using the fully relativistic multi-configuration Dirac–Fock method(MCDF). An appropriate electron correlation model is constructed with the aid of the active space method, which allows the electron correlation effects to be studied efficiently. The contributions of the electron correlation and the Breit interaction to the transition properties are analyzed in detail. It is found that the two-electron one-photon(TEOP) transition is correlation sensitive. The Breit interaction and electron correlation both contribute significantly to the radiative transition properties of the double K hole state of the He-like ions. Good agreement between the present calculation and previous work is achieved. The calculated data will be helpful to future investigations on double K hole decay processes of He-like ions.

Correlation effects on the fine-structure splitting within the 3d9 ground configuration in highly-charged Co-like ions

A comprehensive theoretical study of correlation effects on the fine-structure splitting within the ground configuration 3d9 of the Co-like HI45＋, Ta46＋, W47＋, and Au52＋ ions is performed by employing the multi-configuration Dirac-Hartree- Fock method in the active space approximation. It shows that the core-valence correlation with the inner-core 2p electron is more significant than with the outer 3p and 3s electrons, and the correlation with the 2s electron is also noticeable. The core-core correlation seems to be small and can be ignored. The calculated 2D3/2,5/2 splitting energies agree with the recent electron-beam ion-trap measurements [Phys. Rev. A 83 032517 （2011）, Eur. Phys. J. D 66 286 （2012）] to within the experimental uncertainties.

Isotope shift of the 2s^(2)S_(1/2)→ 2p^(2)P_(1/2,3/2) transitions of Li-like Ca ions

The mass-and field-shift parameters of the two 2s^(2)S_(1/2)→ 2p^(2)P_(1/2,3/2) transitions in the Li-like Ca ions are calculated by using multi-configuration Dirac-Hartree-Fock(MCDHF) and the relativistic configuration interaction(RCI) methods with the inclusion of the transverse photon(Breit) interaction,vacuum polarization and self-energy corrections.In addition,the mass shift and field shift of these two transitions are calculated,where the field shift is calculated by using the evaluated value δ(r^(2)) obtained by [Atomic Data and Nuclear Data Tables 99 69(2013)].It is found that the mass shift of Li-like Ca ions is greater than the field shift.

Study of Inner-Shell Excitation and Relaxation Processes in Atomic and Ionic Neon by Means of Soft X-Ray Spectroscopy

By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regions of the [1s]np （n = 3, 4,…, ε） excited states and [1s2p]3pmp （m = 3,4） doubly excited states to obtain the spectroscopic information on the [2p]np and [2p^2]3prnp final electronic states, where square brackets indicate hole states. The energy levels of the [2p^2]3prnp （m = 3,4） electronic states were spectroscopically measured for the first time. As for the ionic neon target, on the other hand, the photoion yield spectroscopy was adopted to survey the 1s→ np （n = 2, 3） resonant excitation and subsequent Auger decay processes for Ne^＋ target-ions. The observed Ne^2＋ photoion yield spectrum is successflllly explained by the theoretical calculations based on the nmlticonfiguration Dirac-Fock method

Excitation and decay dynamics of 1s2s inner-shell double-vacancy states of neon atoms

The photo-excitation and Auger decay processes of inner-shell double vacancy states 1s2s2p^6（1,3^S）3s3p of neutral neon atoms have been studied theoretically. Multi-configuration Dirac-Fock （MCDF） calculations have been carried out, with electron correlation effects taken into consideration. The relaxation of core and excited orbitals and configuration interaction are found to be crucial to creating the double vacancy states by single photo-absorption. The predominant decay paths for the double vacancy states turn out to be of the LLM Auger decay to 1s 2s^22p^53s（3p）, KLL Auger decay to 1s^22s2p^43s3p, and KLM Auger decay to 1s^22p^63s（3p）. They lead to further Auger decay, creating the neon ions of multiple charge states. For both double and single vacancy states the spectator type of Auger process is dominated in all the Auger decay processes. Theoretical Anger electron spectra are presented for further investigations, experimental and theoretical.

An ab initio investigation of the low-lying electronic states of BeH

Potential energy curves （PECs） for the ground state （X2∑＋） and the four excited electronic states （A2∏, B2∏, C2∑＋, 4∏） of a Bell molecule are calculated using the multi-configuration reference single and double excited configuration interaction （MRCI） approach in combination with the aug-cc-pVTZ basis sets. The calculation covers the internuclear distance ranging from 0.07 nm to 0.70 nm, and the equilibrium bond length Re and the vertical excited energy Te are determined directly. It is evident that the X2∑＋, A2∏, B2∏, C2∑＋ states are bound and 4∏ is a repulsive excited state. With the potentials, all of the vibrational levels and inertial rotation constants are predicted when the rotational quantum number J is set to be equal to zero （J = 0） by numerically solving the radial SchrSdinger equation of nuclear motion. Then the spectroscopic data are obtained including the rotation coupling constant w e, the anharmonic constant WeXe, the equilibrium rotation constant Be, and the vibration-rotation coupling constant ae. These values are compared with the theoretical and experimental results currently available, showing that they are in agreement with each other.

A Numerical Study for Dielectronic Recombination Processes in He-Like Argon

Ab initio calculations of dielectronic recombination(DR)processes from the ground state 1s 2 of He-like argon ion through doubly excited states 1s2snl,1s2pnl(n=2 to 9)of Li-like argon ions are performed using the multi-configuration HatreeFock method with relativistic correction.The theoretical method and its corresponding computation will be outlined.For higher doubly excited states with n>9,the scaling law is used to extrapolate the Auger and radiative transition rates.The total and stateto-state cross sections with corresponding rate coefficients in the temperature from 102 eV to 106 eV are presented,as well as the DR strengths for all the separate resonances.Moreover,peculiarities of the DR from doubly excited 1s2s3l′configurations are analyzed and the contributions of two-electron-one-photo(TEOP)radiative transitions to the DR cross sections are also investigated,such as 1s2s^(2)→1s^(2)2p,due to the strong configuration interactions.Our theoretical results appear to be in excellent agreement with the previous and recent experimental measurements.