QED calculation of then=1andn=2energy levels in He-like ions

Abstract

We perform ab initio QED calculations of energy levels for the n = 1 and n = 2 states of He-like ions with the nuclear charge in the range Z = 12-100. The complete set of two-electron QED corrections is evaluated to all orders in the parameter αZ. Uncalculated contributions to energy levels come through orders α 3 (αZ) 2 , α 2 (αZ) 7 , and higher. The calculation presented is the first treatment for excited states of He-like ions complete through order α 2 (αZ) 4 . A significant improvement in accuracy of theoretical predictions is achieved, especially in the high-Z region.

Energy levels and transition rates for helium-like ions withZ = 10–36

“…In Fig. 2 we compare our results for the excitation energies of these levels to experiments and to two other theoretical valuesthe nonrelativistic approach with an approximate solution to the QED shifts based on one-electron approximation used by Drake (1988) and the ab initio QED approach performed by Artemyev et al (2005). Our MBPT energy levels and the experimental results agree as well as the other two more elaborate and focused (on these levels) other calculations.…”

“…Our MBPT energy levels and the experimental results agree as well as the other two more elaborate and focused (on these levels) other calculations. Although our MBPT values are slightly lower at the low-Z end, which may be due to the Comparisons of our MBPT and some experimental energy levels (square, see references below) for 1s2p 1 P 1 , 1s2p 3 P 1 , 1s2p 3 P 2 , 1s2s 3 S 1 , as well as the comparisons with theoretical values from Drake (1988; solid line) and Artemyev et al (2005; dashed line). The experimental energy levels for 1s2p 1 P 1 are taken from Epp et al (2015) and those reviewed by Beiersdorfer & Brown (2015).…”

“…The systematic A&A 592, A141 (2016) theoretical studies are mostly confined to the n = 2 complex (e.g., Drake 1988;Chen et al 1993;Cheng et al 1994;Plante et al 1994;Johnson et al 1995;Cheng & Chen 2000;Artemyev et al 2005). There are also some large-scale calculations involving n > 2 singly excited levels of helium-like ions.…”

Relativistic configuration-interaction calculations of the energy levels of the 1s22l and 1s2l2l′Yerokhin1, Surzhykov2, Müller3 2017Phys. Rev. ASelf Cite3210333View full textAdd to dashboardCite

“…In order to obtain QED shifts to the total energies, we added results from Refs. [26,27] for the ionization energy of the corresponding He-like ions and results from Ref. [28] son, we conclude that the QEDMOD package reproduces results of rigorous QED calculations for the total energies to accuracy of better than 1%.…”

Parity-nonconservation effect in the dielectronic recombination of polarized electrons with heavy He-like ions

“…The highly accurate values of ∆E (He) , including all second-order two-electron QED contributions, were taken from Ref. [26]. We also have taken into account the mixing of the close-lying (1s2sns) 1/2 and 1s2p 1/2 np 1/2 1/2 levels, as well as the 1s2p 1/2 ns 1/2 and 1s2snp 1/2 1/2 levels (see Ref.…”