Relativistic Hartree–Fock and model-potential ionization energies and oscillator strengths for transitions in the principal, sharp, and diffuse series of neutral rubidium and silver with allowance for core polarization

1979 ◽  
Vol 57 (10) ◽  
pp. 1708-1718 ◽  
Author(s):  
J. Migdałek ◽  
W. E. Baylis
Keyword(s):  
Model Potential ◽  
Oscillator Strengths ◽  
Core Polarization ◽  
Ionization Energies ◽  
Hartree Fock ◽  
Dipole Moment Operator ◽  
Exchange Effects ◽  
Moment Operator ◽  
The One ◽  
Single Configuration

Relativistic single-configuration Hartree–Fock computations of ionization energies and oscillator strengths for transitions in principal, sharp, and diffuse series of neutral rubidium and silver spectra have been performed both with and without allowance for core polarization and are compared with several model-potential calculations. The effect of polarization of the atomic core by the valence electron is included by introducing a polarization potential in the one-electron Hamiltonian and by employing the corresponding correction to the dipole-moment operator of the transition. The results obtained compare well with available experimental data and indicate a significant influence of core polarization on both ionization energies and oscillator strengths. The inclusion of polarization and exchange effects in the model-potential approach and the choice of free parameters is discussed.

scholarly journals Extended theoretical transition data in C i–iv

2021 ◽  
Vol 502 (3) ◽  
pp. 3780-3799
Author(s):  
W Li ◽  
A M Amarsi ◽  
A Papoulia ◽  
J Ekman ◽  
P Jönsson
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Internal Validation ◽  
Hartree Fock ◽  
Relativistic Configuration ◽  
The Difference ◽  
The One ◽  
Relative Differences

ABSTRACT Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C i–iv. The Multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods were used in this work. To improve the quality of the wavefunctions and reduce the relative differences between length and velocity forms for transition data involving high Rydberg states, alternative computational strategies were employed by imposing restrictions on the electron substitutions when constructing the orbital basis for each atom and ion. Transition data, for example, weighted oscillator strengths and transition probabilities, are given for radiative electric dipole (E1) transitions involving levels up to 1s22s22p6s for C i, up to 1s22s27f for C ii, up to 1s22s7f for C iii, and up to 1s28g for C iv. Using the difference between the transition rates in length and velocity gauges as an internal validation, the average uncertainties of all presented E1 transitions are estimated to be 8.05 per cent, 7.20 per cent, 1.77 per cent, and 0.28 per cent, respectively, for C i–iv. Extensive comparisons with available experimental and theoretical results are performed and good agreement is observed for most of the transitions. In addition, the C i data were employed in a re-analysis of the solar carbon abundance. The new transition data give a line-by-line dispersion similar to the one obtained when using transition data that are typically used in stellar spectroscopic applications today.

Relativistic oscillator strengths for np2 → np(n + 1)s transition array of SnI and PbI spectra in jj and intermediate coupling

1979 ◽  
Vol 57 (2) ◽  
pp. 147-151 ◽  
Author(s):  
J. Migdałek
Keyword(s):  
Transition Probabilities ◽  
Theoretical Data ◽  
Wave Functions ◽  
Oscillator Strengths ◽  
Intermediate Coupling ◽  
Hartree Fock ◽  
Semiempirical Approach ◽  
Exchange Effects ◽  
Relativistic Oscillator ◽  
Transition Array

The relativistic oscillator strengths for the np2 → np(n + 1)s transition array as well as the lifetimes of levels of the np(n + 1)s configuration in SnI and PbI spectra were calculated in jj and intermediate coupling. The relativistic radial integrals were computed employing the wave functions obtained by a semiempirical approach which allowed for exchange effects. The results obtained are compared with existing experimental and theoretical data. The significance of intermediate coupling for oscillator strengths computations is discussed. The agreement with experiment is for the present semiempirical results generally better (particularly for the PbI spectrum) than for oscillator strength deduced from 'Optimized Hartree–Fock–Slater' transition probabilities, which were published previously.

Influence of relativistic valence-core correlation on p-state fine structure in some univalent systems

1981 ◽  
Vol 59 (6) ◽  
pp. 769-774 ◽  
Author(s):  
J. Migdalek ◽  
W. E. Baylis
Keyword(s):  
Fine Structure ◽  
Valence Electron ◽  
Closed Shell ◽  
Polarization Potential ◽  
Atomic Core ◽  
Hartree Fock ◽  
The Core ◽  
Ab Initio Approach ◽  
The One ◽  
Single Configuration

Single-configuration relativistic Hartree–Fock values of fine-structure separations are calculated for p-levels in systems with a single electron outside a closed-shell core, both with and without allowance for relaxation and polarization of the core. Effects of the polarization of the atomic core by the valence electron are included by the addition of a polarization potential to the one-electron Hamiltonian. The results obtained generally compare well with available experimental data and indicate a significant influence of core polarization on fine-structure splittings. Contributions of the relaxation of the core are considerable only for the heavier systems. The choice of the cut-off parameter r0 in the polarization potential, as well as of the shape of the cut-off function, and the success of the ab initio approach are discussed. It is suggested that for indium and thallium, in contrast to the case for rubidium, silver, and gold, the simplified picture of a core plus a single valence electron is no longer entirely satisfactory.

Theoretical relativistic oscillator strengths I. Transitions in principal, sharp, and diffuse series of Al I, Ga I, In I, and Tl I spectra

1976 ◽  
Vol 54 (2) ◽  
pp. 118-129 ◽  
Author(s):  
J. Migdałek
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Principal Series ◽  
Semiempirical Method ◽  
Oscillator Strengths ◽  
Relative Line ◽  
Exchange Effects ◽  
The One ◽  
Relativistic Oscillator ◽  
Good Agreement

The oscillator strengths for the sharp, principal, and diffuse series in the spectra of Al I, Ga I, In I, and Tl I are calculated as well as the lifetimes of their lowest excited states. The wave functions that were used were calculated by employing a relativistic semiempirical method which included exchange effects. Very good agreement with the most reliable experimental data was obtained for the fik values in the sharp series as well as for the calculated lifetimes. The discrepancies in the diffuse series are ascribed to the failure of the one-electron approach in the case of strongly perturbed series. The observed deviations in the relative line strengths from the values predicted neglecting the spin–orbit interaction were also investigated. Some systematic trends in the calculated oscillator strengths that were found for the sharp and principal series appear to be corroborated by experimental data for the sharp series in the spectra of Al I, Ga 1, In I.andTl 1.

Core polarization, relaxation, and relativistic effects in the first ionization potentials for some systems in Cu, Ag, and Au isoelectronic sequences

1982 ◽  
Vol 60 (9) ◽  
pp. 1317-1322 ◽  
Author(s):  
J. Migdalek ◽  
W. E. Baylis
Keyword(s):  
Ionization Potential ◽  
Valence Electron ◽  
Relativistic Effects ◽  
Polarization Potential ◽  
Ionization Potentials ◽  
Dipole Polarizability ◽  
Core Polarization ◽  
Hartree Fock ◽  
The Core ◽  
Single Configuration

Single-configuration relativistic Hartree – Fock values of the first ionization potentials for Cu through Kr7+, Ag through 16+, and Au through Pb3+ are computed in "frozen" and "relaxed core" approximations with and without allowance for core polarization. Effects of the polarization of the atomic core by the valence electron are included by introducing a polarization potential in the one-electron Hamiltonian of the valence electron. The core polarization potential depends on two parameters, the static dipole polarizability of the core α and the cut-off radius r0, which are chosen independently of the ionization potential data. It is demonstrated that by including the core polarization potential with a and r0 parameters which are simply chosen instead of being empirically fitted, it is still possible to account, on the average, for at least 70% of the discrepancy between the single-configuration relativistic Hartree – Fock ionization potentials and the experiment, a discrepancy usually ascribed to the contribution of valence-core electron correlations, and to bring the theoretical ionization potentials to an average agreement with experiment of around 1%. The core polarization contribution to ionization potentials is also compared with the contribution of the relaxation of the core and with relativistic effects. An estimate of 55.0 ± 0.1 eV is suggested as the best value of the ionization potential of Sb4+.

Radiative lifetimes, branching fractions, and oscillator strengths of high-lying levels in Re I

2019 ◽  
Author(s):  
Yongfan Li ◽  
Sébastien Gamrath ◽  
Patrick Palmeri ◽  
Pascal Quinet ◽  
Qiu Li ◽  
...  
Keyword(s):  
Transition Probabilities ◽  
Branching Fractions ◽  
Laser Induced Fluorescence ◽  
Oscillator Strengths ◽  
Core Polarization ◽  
Radiative Lifetimes ◽  
Time Resolved ◽  
Hartree Fock ◽  
Semi Empirical ◽  
First Time

Abstract Radiative lifetimes of 19 levels in Re I were measured using the time-resolved laser-induced fluorescence method. As far as we know, 15 results are reported for the first time. By combining the experimental lifetimes determined from the present work with theoretical branching fractions obtained by a pseudo-relativistic Hartree–Fock model including core-polarization contributions, a new set of semi-empirical transition probabilities and oscillator strengths for 47 Re I lines from 18 newly measured levels were derived.

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