Role of triple excitations in calculating different properties of Ba+

TL;DR

This study evaluates the impact of triple excitations on calculating properties of Ba+ using advanced coupled-cluster methods, highlighting computational challenges and providing guidelines for future theoretical predictions in similar systems.

Contribution

It introduces a detailed analysis of triple excitations' effects on Ba+ properties using relativistic coupled-cluster methods and discusses computational restrictions and correction strategies.

Findings

Triple excitations significantly affect energy and property calculations.

Computational restrictions influence the accuracy of results.

Formulated rules for future calculations with limited experimental data.

Abstract

We carried out calculations of the energies, hyperfine structure constants and electric-dipole transiton amplitudes for the low-lying states of Ba+ in the framework of the relativistic linearized coupled-cluster single double (LCCSD) and coupled-cluster single double (valence) triple (CCSDvT) methods. Taking into account that an iterative inclusion of the valence triples into consideration is a complicated and computationally demanding process we study the effects of computational restriction on the final results. We also present a detailed study of various corrections to all calculated properties and use our results to formulate several broad rules that can be used in future calculations of the elements where experimental data are scarce and correct theoretical predictions are highly important.