Orbit-Orbit Interactions in Atomic Spectra

Empirical spectroscopic evidence suggests the existence of an orbit-orbit interaction between electrons, of the form αl₁·l₂, and of a magnitude comparable to the spin-orbit interaction. The direct magnetic interaction is of this form, but previous calculations have yielded too small a magnitude. We suggest that the magnetic interaction is uniquely sensitive to the correlation of the interacting electrons, and that introduction of a reasonable correlation in the wave function may well increase the magnetic interaction to the magnitudes required by the empirical data.