Multiconfiguration calculations of electronic isotope shift factors in   Al I
  The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of electronic isotope shift factors for a set of transitions between low-lying states in neutral aluminium. These electronic quantities together with observed isotope shifts between different pairs of isotopes provide the changes in mean-square charge radii of the atomic nuclei. Two computational approaches are adopted for the estimation of the mass- and field shift factors. Within these approaches, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy and estimate theoretical error bars of the isotope shift factors. 
Livio Filippin, Randolf Beerwerth, J\"orgen Ekman, Stephan Fritzsche,   Michel Godefroid, and Per J\"onsson
physics.atom-ph