The calculation of parameters for Stevens Hamiltonian in a crystalline   field generated by the electric charge uniformly extended in one direction
  Exact expressions for the parameters of Stevens Hamiltonian are derived within the framework of a specific model that assumes uniform character of charge density distribution in a certain direction over crystalline lattice. The new model is developed to strengthen the possibilities for analysis of experimental data obtained by inelastic neutron scattering. It is particularly valuable for studying the charge distribution in the layered perovskite-like compounds doped with the rare-earth ions being used as a local probe. 
V.Bobrovskii, A.Mirmelstein, A.Podlesnyak and I.Zhdakhin