  It has been shown that relativistic spin-orbit effects have enormous
influence on the electronic structure of the correlated electron systems 3dn.
The s-o coupling produces the fine electronic structure with a large number of
low- energy, < 10 meV, localized states, These states affect enormously
electronic and magnetic properties of 3d-ion compounds at low- and
room-temperature regions. It is inferred that the relativistic s-o effects and
the multiplet structure on individual atoms are indispensable for the proper
evaluation of the electronic structure of paramagnetic 3d ions.
