Inclusion of term interaction

According to Figgis [5] one can consider a limited configuration interaction starting from the weak-field kets 

In the weak-field limit with e = —6Dq one gets C = 0. On the contrary, the strong-field limit with e = —8Dq yields C = 1/2 (Fig. 8.21). 

Terms of the susceptibility formula for the intermediate crystal field 

In the case of the intermediate field Figgis [5] derived the magnetic susceptibility formula in the form (Table 8.38) 

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