Relativistic configuration-interaction calculations of energy levels of the $1s^22l$ and $1s2l2l'$ states in lithium-like ions: carbon through chlorine

TL;DR

This paper systematically calculates energy levels of lithium-like ions from carbon to chlorine using relativistic configuration-interaction methods, including QED corrections, providing highly accurate data especially for core-excited states.

Contribution

It introduces a relativistic-configuration-interaction approach with QED corrections for lithium-like ions, improving accuracy for core-excited states beyond current experimental data.

Findings

Results agree with existing high-precision data for ground and first excited states.

Theoretical accuracy surpasses current experimental measurements for core-excited states.

Systematic uncertainty estimation for each state and nuclear charge.

Abstract

We present systematic calculations of energy levels of the $1s^22l$ and $1s2l2l'$ states of ions along the lithium isoelectronic sequence from carbon till chlorine. The calculations are performed by using the relativistic-configuration-interaction method adapted to the treatment of autoionizing core-excited states. The relativistic energies are supplemented with the QED energy shifts calculated within the model QED operator approach. A systematic estimation of the theoretical uncertainties is performed for every electronic state and every nuclear charge. The results are in agreement with existing high-precision theoretical and experimental data for the ground and first excited states. For the core-excited states, our theory is much more accurate than the presently available measurements.