Complex oxides with perovskite and Kagome lattice structures are of special interest due to the presence of geometrical frustrations of the spin magnetic moment in them. The Stevens formalism and Walter parameterization were used to obtain the eigenvalues of the energy of 4f electrons of the rare-earth ion Yb3+ of the complex oxide Yb2Ti2O7. The obtained complete set of solutions to the inverse problem for six Stevens parameters allowed establishing the incompleteness of the existing solutions in the Stevens parameterization for this system. The expected number of necessary experimental parameters was estimated.
Tovstogan et al. (Mon,) studied this question.