Precision calculation of hyperfine constants for extracting nuclear moments of 229Th

TL;DR

This paper enhances the precision of hyperfine constant calculations for 229Th by incorporating an iterative solution into the relativistic coupled-cluster method, leading to more accurate nuclear moment determinations.

Contribution

It introduces an iterative solution for core triple cluster amplitudes in the relativistic coupled-cluster method, improving nuclear moment calculations for 229Th.

Findings

Calculated nuclear magnetic dipole moment: 0.366(6) μ_N

Calculated nuclear quadrupole moment: 3.11(2) eb

Reduced quadrupole moment uncertainty by a factor of three

Abstract

Determination of nuclear moments for many nuclei relies on the computation of hyperfine constants, with theoretical uncertainties directly affecting the resulting uncertainties of the nuclear moments. In this work we improve the precision of such method by including for the first time an iterative solution of equations for the core triple cluster amplitudes into the relativistic coupled-cluster method, with large-scale complete basis sets. We carried out calculations of the energies and magnetic dipole and electric quadrupole hyperfine structure constants for the low-lying states of 229Th^(3+) in the framework of such relativistic coupled-cluster single double triple (CCSDT) method. We present a detailed study of various corrections to all calculated properties. Using the theory results and experimental data we found the nuclear magnetic dipole and electric quadrupole moments to be mu = 0.366(6)*mu_N and Q = 3.11(2) eb, and reducing the uncertainty of the quadrupole moment by a factor of three. The Bohr-Weisskopf effect of the finite nuclear magnetization is investigated, with bounds placed on the deviation of the magnetization distribution from the uniform one.