For some rare earth ions and for transition metals or actinides it is necessary to
include more singleion ion states with differen L,S into the calculation. This
can be done in intermediate coupling using the module *ic1ion*, which
explicitely includes electrostatic and spin orbit interactions for each ion:

Here , and denote the number of electrons, the charge of the nucleus and the position of the ion number ,respectively, for each electron being the momentum, the mass, the charge and the location. Spin orbit coupling is written in terms of the orbital momentum and spin of the individual electrons. The Zeman interaction and two ion interaction are written in terms of the (inverse) total spin and (inverse) total orbital momentum of ion number . The crystal field in intermediate coupling is written in terms of Wybourne parameters and Wybourne operators , operator equivalents of real valued spherical harmonic functions , for the ion , for details on crystal field parameter conventions see appendix E.

Martin Rotter 2017-01-10