Combination of the single-double coupled cluster and the configuration interaction methods; application to barium, lutetium and their ions

TL;DR

This paper introduces a combined computational method merging coupled cluster and configuration interaction techniques to accurately calculate energy levels of barium, lutetium, and their ions, demonstrating good agreement with experimental data.

Contribution

The paper presents a novel combined approach integrating coupled cluster and configuration interaction methods for improved atomic energy level calculations.

Findings

Accurate energy level calculations for Ba, Ba+, Lu, Lu+, and Lu2+.

Good agreement with experimental data.

Comparison shows improvements over previous methods.

Abstract

A version of the method of accurate calculations for few valence-electron atoms which combines linearized single-double coupled cluster method with the configuration interaction technique is presented. The use of the method is illustrated by calculations of the energy levels for Ba, Ba$^+$, Lu, Lu$^+$ and Lu$^{2+}$. Good agreement with experiment is demonstrated and comparison with previous version of the method (Safronova {\em et al}, PRA {\bf 80}, 012516 (2009)) is made.