Ab-initio calculations of Judd-Ofelt intensity parameters for transitions between crystal-field levels

Wavefunction-based ab-initio calculations of the electric-dipole moments of 4fN-4fN transitions of lanthanide ions are performed to extract the Atpλ intensity parameters. The extraction method is an extension of our earlier calculations of crystal-field (CF) parameters for lanthanide ions in crystals. The CASSCF/RASSI-SO (Complete-Active-Space Self-Consistent-Field/Restricted-Active-Space State-Interaction Spin-Orbit) calculations have been carried out on the chosen model system of CaF2: Ce3+ with an interstitial fluoride ion (Fi−) on z-axis (Ce3+ ion occupying the C4v symmetry site). In consideration of the site symmetry and the coordination situation of Ce3+ ion at C4v site in CaF2 as well as the superposition model (SM), the calculated intensity parameters for Ce3+ ion can be classified into three categories, and detailed discussions are then given.