Electronic structure of the lanthanide and actinide ions

There is another way of looking at this. In symmetry the f orbitals transform as 2u + Tiu + T2 . Reduce the symmetry by a distortion (compression or elongation, for example) along a fourfold axis so that the symmetry is now 1)4. The f orbitals now transform as (Bi ) + ( 2 + m) + B2U + F ), where the brackets correspond, in order, to the symmetries in 0 given above. It can be seen that two different sets of f orbitals have symmetry. Because they have the same symmetry they can mix and it proves convenient to let them do this and to work with combinations of them. As a result, some differently shaped f orbitals arise. The members of this so-called general set of f orbitals are shown in Fig. 11.3, where both their abbreviated and complete labels are given. 

Although the idea can be over-emphasized, there is little doubt that f 

Had the f electrons in complexes of the lanthanides and actinides experienced crystal fields comparable to those in complexes containing d electrons, we would next have to include these fields, just as was done in Chapters 7 and 8. But these fields are small—much more important 

Ion f electron Angular momentum Total orbital Term associated 

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