Calculation of hyperfine structure constants for ytterbium
  We calculate energies and hyperfine structure constants A and B for low-lying levels of $^{173}$Yb. The latter is treated as a two-electron atom. To account for valence-valence correlations the configuration interaction method is used. Valence-core correlations are accounted for within the many-body perturbation theory which is used to construct effective two-electron operators in the valence space. 
S.G.Porsev, Yu.G.Rakhlina and M.G.Kozlov (Petersburg Nuclear Physics   Institute)