Combination of the single-double coupled cluster and the configuration   interaction methods; application to barium, lutetium and their ions
  A version of the method of accurate calculations for few valence-electron atoms which combines linearized single-double coupled cluster method with the configuration interaction technique is presented. The use of the method is illustrated by calculations of the energy levels for Ba, Ba$^+$, Lu, Lu$^+$ and Lu$^{2+}$. Good agreement with experiment is demonstrated and comparison with previous version of the method (Safronova {\em et al}, PRA {\bf 80}, 012516 (2009)) is made. 
V. A. Dzuba
physics.atom-ph