Application of a Relativistic Coupled-Cluster Theory to the Effective   Electric Field in YbF
  An accurate determination of the effective electric field (Eeff) in YbF is important, as it can be combined with the results of future experiments to give an improved new limit for the electric dipole moment of the electron. We report a relativistic coupled-cluster calculation of this quantity in which all the core electrons were excited. It surpasses the approximations made in the previous reported calculations. We obtain a value of 23.1 GV/cm for Eeff in YbF with an estimated error of less than 10%. The crucial roles of the basis sets and the core excitations in our work are discussed. 
M. Abe, G. Gopakumar, M. Hada, B. P. Das, H. Tatewaki, D. Mukherjee
physics.atom-ph