Hyperfine structure of S states in Li and Be^+

TL;DR

This paper presents a comprehensive large-scale CI calculation of hyperfine splitting in Li and Be+ ions, incorporating relativistic, QED, nuclear, and recoil effects, achieving highly accurate theoretical predictions.

Contribution

It introduces an advanced CI approach combined with various corrections, providing more precise hyperfine splitting values than previous studies.

Findings

Results agree well with nonrelativistic variational calculations.

Theoretical values are complete to order α^2.

Improved accuracy over prior research.

Abstract

A large-scale configuration-interaction (CI) calculation is reported for the hyperfine splitting of the 2^2S and 3^2S states of ^7Li and ^9Be^+. The CI calculation based on the Dirac-Coulomb-Breit Hamiltonian is supplemented with a separate treatment of the QED, nuclear-size, nuclear-magnetization distribution, and recoil corrections. The nonrelativistic limit of the CI results is in excellent agreement with variational calculations. The theoretical values obtained for the hyperfine splitting are complete to the relative order of \alpha^2 and improve upon results of previous studies.