Mutual spin-orbit and spin-spin interactions in atomic structure calculations

This is the authors' abstract. We don't add key points for this paper.

A method of including the spin-spin and spin-other-orbit interactions of the Breit-Pauli hamiltonian in the calculation of bound states of atomic systems is described. It represents an extension of a program described recently by Jones, in which energy levels of complex atoms are calculated with relativistic corrections. The same powerful and versatile computing techniques are employed, and expressions for the spin-spin and mutual spin-orbit interactions are given in forms suitable for application of these techniques. Some illustrative numerical results are given, showing that an appreciable improvement may be obtained by including these operators. In the case of Fe VI it is shown that more extensive nonrelativistic calculations including correlation effects will be necessary before wholly satisfactory calculations of fine structure are possible.