Using Gaussian decompositions of the electron potential energy and the 4f and 5d-electron wave functions, we have derived short analytical formulae for calculating the parameters of the odd crystal field on rare-earth ions. Extended charge contributions to the intrinsic parameters a⁽¹⁾, a⁽²⁾, a⁽³⁾, a⁽⁴⁾, a⁽⁵⁾, and a⁽⁶⁾ were evaluated using Hartree-Fock wave functions of Pr³⁺-O^2- and of Tm³⁺-O^2- pairs.

n approximation of a distribution of zero field splitting (ZFS) parameters by using two-dimensional normal distributions in discrete representation is proposed. The results of modelling the X-band EPR spectra of human serum transferrin are in a good accordance with experiment. For a number of studied EPR spectra, it was found that the desired distribution consists of two components with various rhombicity parameters. The first component is characterized by a relative high degree of correlation between the parameters E and D. For the second component of ZFS, which we associate with iron bound to the C-lobe iron site of human serum transferrin, a high dispersion of the correlation coefficient is observed.

This article uses density functional theory calculations to explore the structural, electronic, and magnetic features of a ferromagnet/ferroelectric Fe/BaTiO₃ heterostructure, which possesses a complex non-collinear magnetic structure. The presented research focuses on the evolution of spin systems under the influence of external fields, namely the reorientation of magnetic moments driven by electric-field-induced polarization switching and lattice strain. We demonstrated that the electronic and magnetic properties of the thin ferromagnetic Fe film can be effectively tuned by applying an external electric field - simply by altering the polarization direction of the ferroelectric BaTiO₃. By incorporating spin-orbit coupling into the computation scheme, we evaluated the relative structural distortions, magnetic moments in atomic layers, atom- and orbital-resolved density of states, magnetic anisotropy energies, and easy magnetization directions.