Nonlinear and linear shielding of rare-earth crystal-field interactions

Arthur J Freeman, R. E. Watson

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Abstract

It was shown previously that significant nonlinear shielding of the rare-earth electrostatic crystalline-field interactions may occur, and hence that the standard parametrization scheme used to determine the crystalfield parameters, VLM=ALMrL, was questionable. These nonlinear effects arise from the same distortions of the closed shells in rare-earth ions which produce the (larger) linear shielding of the crystal field Vc. In this paper, both nonlinear and linear shielding effects have been investigated for the rare-earth ions Ce3+, and Tb3+ through Yb3+ inclusive. The method of single substituted configurations is employed and is shown to avoid the difficulties associated with the traditional single-determinant perturbation-theory approach previously used exclusively by various authors. Results based on both methods are given and compared; significant differences in linear-shielding predictions are found to be introduced by the inexact traditional approach. Calculations for the nonlinear 5p4f effects have been done, and results displayed, as a function of the strength of Vc (based on the point-charge model). The relevance of these effects to experiment is examined qualitatively.

Original languageEnglish
JournalPhysical Review
Volume139
Issue number5A
DOIs
Publication statusPublished - 1965

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ASJC Scopus subject areas

  • Physics and Astronomy(all)

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