S. Edvardsson et M. Klintenberg, ROLE OF THE ELECTROSTATIC MODEL IN CALCULATING RARE-EARTH CRYSTAL-FIELD PARAMETERS, Journal of alloys and compounds, 277, 1998, pp. 230-233
The Sternheimer method is used to derive shielding parameters and anti
shielding factors for the whale series of rare earths using relativist
ic wavefunctions. It is found that the shielding parameter sigma(2) of
the 4f electronic shell is decreased compared to earlier calculations
. The sigma(4) and sigma(6) parameters are calculated for the first ti
me for all rare-earth ions. In all cases, they are found to be small.
The influence of the various calculated parameters on the crystal-fiel
d parameters for the cases Nd:LiYF4 and Pr:LiYF4 is studied. Present c
orrections result in ab initio crystal-field parameters that are in ex
cellent agreement with experimentally fitted phenomenological paramete
rs. The nuclear antishielding factors gamma(infinity) are found to ess
entially agree with earlier findings. These are also found to agree wi
th some early experiments. The various wavefunctions used are derived
from a relativistic Desclaux code. These are mon external compared to
standard Hartree-Fock wavefunctions. (C) 1998 Elsevier Science S.A.