Approximate first-order trigonal crystal-field-split energy levels are derived and fitted theoretically for the Sm3+-in-CaF2 (Type I) 6H7/2, 6H9/2, and 6H11/2 states of the ground multiplet involved in fluorescence. Crystal-field theory and the Stevens method are employed in this derivation. The resulting energy deviation between the first-order theoretical levels and the empirically derived levels is within 42 cm-1 for 14 of the 15 levels involved under the assumption of a constancy of the six trigonal crystal-field parameters. Tables are given of the resulting approximate values of the crystal-field parameters, level energies, and eigenfunctions.
NORMAN RABBINER, "Trigonal Crystal-Field Energy Levels of Sm3+ in CaF2 (Type 1)," J. Opt. Soc. Am. 59, 588-590 (1969)