Multipole occupation parameters least-squares refined on the basis of X-ray diffraction intensities are combined with orbital occupation parameters obtained from crystal field perturbation-calculations using the model of point charges situated on the atomic positions. As the result preliminary orbital occupation parameters are obtained and these themselves are least-squares refined on the basis of the observed intensities. The point charges are superposed by the charge distributions of the occupied orbitals and the perturbation calculation is again carried out. The crystal field is calculated by summation in reciprocal space. The self potential is taken into account. The perturbation calculation yields besides of orbital occupation parameters also crystal field energy levels. MultipolesThe charge distribution ρ ν (Γ) of a v-th "pseudoatom" in the crystal field may be partitioned into the charge distribution ρ{(τ) of the free atom or ion and its deformation density ζ1ρ ν (Γ): ρ ν (Γ) = ρ{(Γ) + Λρ ν (Γ).(1)The deformation density can be expanded in spherical harmonics + 1 ¿0v(r) = Σ Σ RÌJr)N lm c] m P lm (cosö)^* (2)I m = -I Brought to you by | University of California Authenticated Download Date | 6/7/15 8:37 PM