MAGNETIC MEASUREMENTS AND THE NATURE OF CRYSTAL-FIELD IN ND-2(SO4)(3)CENTER-DOT-8H(2)O

Magnetic measurements on octahydrated neodymium sulphate have been car ried out in the temperature range 80 to 300 K and analysis of the resu lts has been performed using a crystal field of D-4h symmetry. The mos t rigorous approach of direct diagonalization of tile Hamiltonian matr ix constructed in the complete basis of states belonging to all atomic terms of the Nd3+ ion has been employed to evaluate the set of energy level parameters including crystal field parameters. The Hamiltonian consists of terms representing free ion (Coulomb and spin-orbit), crys tal field, and two-body configuration interactions. It has also been d emonstrated that for a correct evaluation of crystal field parameters it is absolutely necessary to work with a complete basis ill the rigor ous framework rather than with a partial basis.