Correlation-crystal-field delta-function analysis of 4f2 (Pr3+) energy-level structure

Standard formulations of the electronic energy-level Hamiltonian, applied to lanthanide systems, have been used with great success in rationalizing observed energy-level splittings and Stark level orderings. However, these standard models do not satisfactorily account for the energy-level structures observed for specific anomalous multiplet manifolds, such as the 1D2 multiplet of Pr3+. In the present study, we apply a simplified correlation-crystal-field model to the 4f2 electronic energy-level structure of Pr3+ in seven different crystalline hosts. This highly restricted form of the correlation-crystal-field (CCF) contribution to the model energy-level Hamiltonian, called the 'δ-function' CCF model, considers two-electron correlation effects only from paired electrons within the same angular orbital, an assumption that reduces the plethora of applicable CCF operators to only two important independent terms. When the 'δ-function' CCF model is applied to the electronic energy-level structures of LaCl3:Pr3+, GdCl3:Pr3+, Cs2NaPrCl6, Cs2NaYCl6:Pr3+, LiYF4:Pr3+, LiBiF4:Pr3+, and CsCdBr3:Pr3+, the major discrepancies between observed and calculated crystal-field splittings in the 1D2 multiplet manifold for each system are successfully resolved. © 1998 Elsevier Science S.A.