Our approach involves the magnetic energy of the spin system (further called system energy) calculated in the frame of the continuous 3D Heisenberg model [23]:(1) E=−∑i,jJijSi⋅Sj−∑iKi(S^i⋅n^i)2−gμBμ0∑iHi⋅Si+D∑i,jSi⋅Sj−3(Si⋅eij)(Sj⋅eij)rij3 where Jij is the exchange parameter, Si is the spin vector on site i, Ki is the anisotropy constant (per site), ni^ is the versor of the easy magnetization axis, Si^ is the versor of the spin, g is the Lande factor, μB is the Bohr magneton, μ0 is the vacuum permeability, Hi is the magnetic field on site i, D is the dipolar constant, eij is the directional versor between the i-th and j-th nodes and rij is the distance between the i-th and j-th nodes.