The problems of the unambiguity of the numerical parametrization of the ESR spin hamiltonian

The numerical method ofthe parametrization calls attention to a question connected with the unambiguity of the parametrization of the spin Hamiltonian. The least square criterion alone does not cope with the choice of the physical solution from the numerical set. For example curve (2) in fig. 1 is by this criterion better than curve (1) but the symmetry of the experimental dependence prefers the solution (1). Another source of the ambiguity lies in the unknown numbers α β in (3) and at fixed α, β the functionfαβ fy can have more than only one minimum.