Figgis isotropic Hamiltonian

Level-4. In the case of the Cl-interacting Ti-terms the Figgis isotropic Hamiltonian reads... 

The improved Figgis isotropic Hamiltonian (Eq. 195) accounting for the Cl of 4 Tig terms can also be applied, and this better accommodates the actual CF strength through the Cl-mixing parameter A. Again a closed form for the magnetic susceptibility is available (Table 25). 

Figgis isotropic Hamiltonian is appropriate to 4Tig term in Cl analytical formula for x =f(A,k) /xeff passes through a maximum (extrapolated TIP is negative). 

For the 2 2g and 5T2g-terms of the Oh-reference the Griffith theory could be appropriate. In the case of the Cl-interacting terms 3Tig or 4 Tig, the Figgis isotropic Hamiltonian can be applied. These theories offer the magnetic susceptibility formulae in closed forms. However, these approaches... 

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... 

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