In two other papers [M. D. Faucher, O. K. Moune, D. Garcia, and P.
Tanner, Phys. Rev. B 53, 9501 (1996); M. D. Faucher and O. K. Moune, J.
Alloys Compounds (to be published)], it was shown that the introduction
of the 5fn/5fn-17p (or
4fn/4fn-16p) configuration interaction eliminated
large discrepancies in the crystal-field analysis of (i) U4+
(5f2) in Cs2UBr6 and
Cs2ZrBr6, for which the least ... [Show full abstract] root-mean-square
deviation between experimental and calculated energy levels falls down
from 241 to 56 cm-1, and (ii) Nd3+ in
Nd2O2S, for which the discrepancy of the
2H(2)11/2 level is eliminated by the configuration
interaction with the excited 4f26p configuration. The
demonstration is now extended to Pr3+ and seems to be of
general application. For LiYF4:Pr3+ the mean
deviation is divided by more than 2 by utilizing an interaction matrix
including 4f6p in addition to the ground configuration 4f2.