Crystal field model, failure

However, applying the same model to the high-pressure results for Sm +, extreme deviations were encountered. The authors attributed these deviations to a breakdown of the spin-correlated crystal-field model for Sm " ". As the reason for this failure, configuration interactions with the 4f 5d configuration were determined. These interactions are expected to be much stronger for Sm " ", because the energy of the excited configuration is much lower (at about 20 000 cm ) than in the case of Eu + (at about 50 000 cm ). 

Whilst there have been several theoretical investigations of the effect of hybridisation on the crystal-field excitations within the ground multiplet (Maekawa et al. 1985, Lopes and Coqblin 1986), there have been relatively few in which the spin-orbit level is explicitly included. Cox et al. (1986) have shown, in the context of the Anderson impurity model, that when is comparable to the spin-orbit splitting, the inelastic peak is broadened and shifted to lower energies. Given that the cross-section is weak, at about half the intensity of the praseodymium spin-orbit cross-section, they concluded that the transition was unlikely to be seen except in heavy-fermion compounds with low values of This appears to be confirmed by the failure to observe such a transition in CePdj in recent measurements on HET (Osborn, unpublished). On the other hand, the... 

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