Improved RCI techniques for atomic 4f \u3c sup\u3e n \u3c/sup\u3e excitation energies and polarizabilities

We propose an efficient method by which previously computationally expensive, but moderately important, pair correlation effects can be incorporated into fn excitation energies. Application is to Gd IV. Secondly, we extend two methods of obtaining static and tensor dipole polarizabilities and apply them to the Ni II ground state. The first uses the sum over the f-values approach, and the second is variational. © 2010 IOP Publishing Ltd