POSSIBILITY OF A REDUCED DESCRIPTION FOR THE SPIN DYNAMICS OF ANISOTROPIC HEISENBERG PARAMAGNETS AND THE SHAPE OF NMR-SPECTRA IN SOLIDS

The problem of the shape of the NMR line in solids has been solved in quadratures. Although the constructed solution is based on exact resul ts obtained by the authors, the possibility for a correct description of experimental data on the basis of lower approximations of the theor y essentially depends on the crystal lattice type. Only the spectra of crystals with ordinary dense lattices (rather than, e.g., quasi-one-d imensional systems) can be adequately described in lower approximation s, which is a very urgent problem. Comparison of theoretical and exper imental results has resulted in good agreement.