Yr. Shen et Kl. Bray, AB-INITIO CALCULATION ON CRYSTAL FIELDS OF SM2+ IN SOLIDS WITH CL ANDF LIGANDS, Physical review. B, Condensed matter, 58(9), 1998, pp. 5305-5313
The linear combination of atomic orbitals (-molecular orbitals) crysta
l-field theory in the context of the superposition model was used to c
alculate the intrinsic crystal-field parameters for Sm2+ ions in solid
s with Cl and F ligands at different interionic distances. The five ma
in contributions: point charge, charge penetration, exchange, overlap,
and covalency considered in the present work can reasonably describe
the experimental results. A direct comparison between divalent and tri
valent lanthanide ions leads to the conclusion that the. initial intri
nsic crystal-field parameters and the power-law exponents correspondin
g to the distance dependence for divalent lanthanide ions are larger t
han those for trivalent lanthanide ions.