Atomic data calculations by Z-expansion method for doubly excited states 2lnl' and 1s2lnl' of highly charged ions with Z=6-36. I. Transitions from the states with n=2,3

TL;DR

This paper presents improved atomic data calculations for doubly excited states in highly charged ions with Z=6-36, incorporating first-order screening corrections and relativistic effects, resulting in more accurate transition probabilities and autoionization rates.

Contribution

The study introduces a modified MZ code that accounts for first-order 1/Z corrections and relativistic effects, enhancing the accuracy of atomic data for doubly excited states.

Findings

New autoionization rates are 20-50% lower than previous calculations.

Calculated data agree within 10% with multi-configuration methods.

Refinements improve energies and transition probabilities for ions with Z=6-36.

Abstract

The wavelengths and radiative transition probabilities for transitions 2lnl'-1snl", 2lnl'-1s2l", 1s2lnl'-1s^2.nl", 1s2lnl'-1s^2.2l", and the autoionization decay probabilities for doubly excited states 2lnl', 1s2lnl' were calculated in ions with atomic numbers Z=6-36 for n=2-10, l'=0-3. The calculations were carried out by means of the MZ code based on the Z-expansion method. Relativistic corrections were taken into account within the framework of the Breit operator. The main difference with previous calculations by MZ code consists in accounting for the first order corrections in powers of 1/Z, corresponding to the screening effects, in calculations of autoionization rates. New data for comparatively large rates are about 20-50% less as compared to previous ones and are in a agreement within 10% with the results of calculations made by the methods based on multi-configuration wave functions with non-relativistic and relativistic orbitals. Some refinements and corrections concerning the energies and radiative transition probabilities were also introduced in the MZ code. In this paper the main formulas used in a modified MZ-code and the data needed for description of dielectronic satellites with n=2,3 are given; the data for higher n will be presented in the following publications.