First-principles theory of antishielding effects in the nuclear quadrupole interaction in ionic crystals: Application to /sup 57m/Fe in Fe/sub 2/O/sub 3/

Journal Article · Thu Sep 01 00:00:00 EDT 1983 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.28.2335· OSTI ID:5558144

Beri, A C; Lee, T; Das, T P; Sternheimer, R M

A first-principles procedure is developed for the quantitative study of the widely differing Sternheimer antishielding effects that can be ascribed to the induced electric field gradients due to the various sources of electric field gradient in ionic crystals. The method involves the perturbation of the electronic states in the crystal by the nuclear quadrupole moment of the central ion, and the use of these perturbed functions in an evaluation of components of the energy of the crystal which are linear in the quadrupole moment. With each term in this energy, one can associate an induced field gradient due to a specific source in the crystal and a specific perturbation of the central-ion charge distribution. We have applied this ab initio method to a study of the nuclear quadrupole interaction for /sup 57m/Fe in Fe/sub 2/O/sub 3/ using a model in which an Fe/sup 3 +/ ion is surrounded by six O/sup 2 -/ ligands whose charge distributions overlap the Fe/sup 3 +/ ion. The application of our procedure to the model of overlapping ions leads to the important conclusion that the field gradients due to the various sources in the central cluster and the surrounding lattice are all subject to very different antishielding effects. The sources involved can be grouped broadly into three classes: local, nonlocal, and distant, with the local sources involving charge densities purely central in character, nonlocal sources involving charge densities composed of one central-ion orbital and one ligand-ion orbital, and the distant sources involving two categories, a distant electronic one composed of charge densities from purely ligand-ion orbitals, and a distant nuclear one, comprising the nuclear charges on the ligand ions (O/sup 2 -/).

• Research Organization: Department of Physics, State University of New York at Albany, Albany, New York 12222
• OSTI ID: 5558144
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 28:5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRON 57
MOESSBAUER EFFECT
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ELECTRONIC STRUCTURE
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IONIC CRYSTALS
LIGANDS
STERNHEIMER FORMULA
CHALCOGENIDES
CRYSTALS
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