Calculation of energies and hyperfine structure constants of 233U^+ and 233U

TL;DR

This paper compares two advanced computational methods to calculate energies and hyperfine constants of 233U^+ and 233U, addressing the challenges posed by uranium's complex atomic structure.

Contribution

It introduces and analyzes two different approaches for high-precision calculations of uranium ions, highlighting their strengths and limitations.

Findings

Both methods successfully compute energies and hyperfine constants.

The combined CI and perturbation approach effectively includes core-valence correlations.

Preliminary nuclear magnetic moment value suggests further experimental validation.

Abstract

We carried out calculations of the energies and magnetic dipole hyperfine structure constants of the low-lying states of 233U^+ and 233U using two different approaches. With six valence electrons and a very heavy core, uranium represents a major challenge for precision atomic theory even using large-scale computational resources. The first approach combines configuration interaction (CI) with a method allowing us to include core-valence correlations to all orders of the perturbation theory over residual Coulomb interaction. The second approach is a pure CI method which allows the use of different initial approximations. We present a detailed analysis of all calculated properties and discuss the advantages and disadvantages of each of these methods. We report a preliminary value of the U nuclear magnetic moment and outline the need for further experiments.