Core correlation effects in multiconfiguration calculations of isotope shifts in Mg I

TL;DR

This study uses advanced multiconfiguration Dirac-Hartree-Fock calculations to analyze isotope shifts in magnesium, highlighting the importance of including core-core excitations for improved accuracy in transition energies and mass shift factors.

Contribution

It introduces a comprehensive computational approach that incorporates core-core excitations, enhancing the precision of isotope shift predictions in magnesium.

Findings

Core-core excitations significantly improve transition energy accuracy.

Valence and core-valence models are accurate but less precise without core-core effects.

Calculated isotope shifts align well with experimental data when core-core effects are included.

Abstract

The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of isotope shifts for several well-known transitions in neutral magnesium. Relativistic normal and specific mass shift factors as well as the electronic probability density at the origin are calculated. Combining these electronic quantities with available nuclear data, energy and transition level shifts are determined for the $^{26}$Mg$-^{24}$Mg pair of isotopes. Different models for electron correlation are adopted. It is shown that although valence and core-valence models provide accurate values for the isotope shifts, the inclusion of core-core excitations in the computational strategy significantly improves the accuracy of the transition energies and normal mass shift factors.