Screening theory for transition energies of highly charged ions

Abstract

Many body perturbation theory in conjunction with the screening method has been applied to calculate radiative transition energies of highly charged ions. In the formulas obtained the energy values are averaged over LSJ as a function of the number of electrons distributed in up to 27 subshells taking relativistic energy shifts into account. The introduction of approximate screening parameters for nonrelativistic and relativistic parts of the energy allows us to limit our calculation to first order interelectron interaction only. The derived formulas have been proven to be very useful calculating X-ray spectra of Xeq+ (q = 44−48) ions interacting with the Cu surface. Comparison is made with other methods such as Hartree-Fock-Pauli (HFP), and relativistic model potential. Computational problems introducing different screening constants and asymptotic limits as well as contributions of the neglected second order interaction are discussed.

An efficient screening approach to be used in plasma modeling and ion-surface collision experiments

“…N * This work [2] This work [2] 10 4607, 80 4647 0 As other example of complex transitions, we show in Table 4 transitions of the type Φ 0 Φ 1 − 2p −1 3dΦ 0 Φ 1 as defined in Reference [2]: Φ 0 = 1s 2 2s 2 2p 6 , Φ 1 = 3d n Φ 0 . Both values are within 1%, but it must be mentioned that the approach of Safronova et al produces very bad values (negatives!)…”

“…Moreover, it should be mentioned that, although a set of f ji and g i j constants could be used (which we have called f ∞ i j and g ∞ i j ), better results are obtained if the f ji and g i j are handled as parameters. Our approach assure this property taking into account the variation with Z and N. However, it is true that for sufficiently ionized atoms, the use of constants provides a very good approximation, useful for plasma modeling and ion-surface collision experiments [2].…”

“…Moreover, relativistic corrections to the energy can be easily made and configuration interaction effects can be properly considered. It is important to point out that several published screening rules produce negative ionization potentials (IP) for neutral or few ionized systems [2] [7]. Other authors obtain the screening parameters either in order to reproduce the IP's calculated by Hartree-Fock [9] [10] or by adjusting analytical potentials with numerical results [11].…”

An efficient screening approach to be used in plasma modeling and ion-surface collision experiments

“…The use of screened hydrogenic models (SHM) for modeling plasmas and surface ion collision experiments has been well documented in recent works [1], [2]. Different methods are available for systematic numerical calculations of atomic parameters, based on the self-consistent Hartree-Fock procedure [3] [4].…”

“…Moreover, relativistic corrections to the energy can be easily made and configuration interaction effects can be properly considered. It is important to point out that several published screening rules produce negative ionization potentials (IP) for neutral or few ionized systems [2] [7]. Other authors obtain the screening parameters either in order to reproduce the IP's calculated by Hartree-Fock [9] [10] or by adjusting analytical potentials with numerical results [11].…”