ABSTRACT
In this chapter we discuss the effects that arise in crystal field theory when one considers relativity. Relativistic crystal field theory1 started with attempts to calculate the electric quadrupole moment of the ground state 4 f 76s2[8S7/2 ] of neutral europium in an atomic beam2,3, a problem very analogous to the crystal field splitting of the ground state 4 f 7[8S7/2 ] of trivalent gadolinium1,4. If we solve Dirac’s equation for an electron nj in a central field, we obtain two radial functions, F and G, which are associated with the small and large components of the Dirac wave function, respectively, and which depend on the total angular momentum j of the electron. Here we consider the simple case of a single electron in an f −orbital and then remark upon some of the consequences in the Judd-Ofelt theory of f ←→ f transitions intensities when looking for effects that go beyond the standard non-relativistic approach.
