Contributions from high angular momentum states to three particle correlation in Pr2+

An infinitely deep potential well surrounding the rare earth ion is used to produce a discrete orthogonal basis set, including the free ion occupied states, in a finite spherical region. The three particle correlation parameters T i for Pr 2+ have been calculated using 81 atomic orbitals of this basis set with l=1,3,5 and 7. Both the l=5 and l=7 states are shown to make a significant contribution to the T i resulting in better agreement between theory and experiment. This work provides an example of a new practical technique for configuration interaction calculations applicable to any problem involving isolated atoms or clusters of atoms.