Figgis anisotropic Hamiltonian

The degenerate ground term needs a treatment within the isotropic Griffith Hamiltonian (Eq. 194) and on a tetragonal distortion within the anisotropic Figgis Hamiltonian (Eq. 196). For representative drawings see... 

Level-5. On a tetragonal distortion the Figgis anisotropic Hamiltonian is appropriate ... 

The magnetism can be modeled with the help of the Figgis anisotropic Hamiltonian (Eq. 196). Its eigenvalues can be expanded in powers to B to... 

The 2B2g term is lifted by the axial CF-splitting ground term is well isolated. Figgis anisotropic Hamiltonian is appropriate analytical formulae for %a =/(v, X,Ka) high anisotropy of /. SH works properly for axial MPs. 

On tetragonal distortion two different reference situations occur as displayed in Fig. 60. For the compressed tetragonal bipyramid the ground CFT is3 g. The magnetism could be modeled with the Figgis anisotropic Hamiltonian (Eq. 196) on the symmetry descent. Much more precise, however, are the calculations in the complete d4 space spanned by 210 functions. These results are displayed in Fig. 61. The magnetic anisotropy is visible far above room temperature. 

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