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Crystal field effects on 4f electrons: Theories and reality

1983; Elsevier BV; Volume: 93; Issue: 1 Linguagem: Inglês

10.1016/0022-5088(83)90445-9

1878-2728

M. Faucher, D. Garcia,

Semiconductor materials and devices

The present methods of calculating crystal field effects in a solid are examined. Several models intermediate between the entirely phenomenological model leading to the determination of the so-called “experimental” crystal field parameters and a complete linear combination of atomic orbitals calculation have been constructed. In these models simplifying hypotheses lead to descriptions of crystal field effects which have some degree of parametricity, so that the term “a priori determination” is sometimes misleading and should be redefined. The most sophisticated models are characterized by the smallest number of a priori assumptions. However, it is questionable whether an increase in sophistication improves the agreement between theory and experiment. Practical methods of calculating crystal field parameters, i.e. in the framework of the electrostatic, angular overlap and weakly covalent models, are described.