Contribution of the Breit interaction to electron scattering from heavy atoms

We have investigated the contribution that the frequency-independent magnetic term of the Breit interaction makes to electron scattering from heavy, closed-shell atoms at low and intermediate energies. We treat the Breit interaction as a perturbation to the scattering phase shifts calculated within a consistently relativistic approximation via the Hulthén-Kato scattering identity. Results are presented for scattering from both xenon and mercury. Although the Breit interaction makes a noticeable contribution to the scattering phase shift, in most cases the difference is not significant on the scale of the accuracy of current experimental measurements. However, we have identified one situation where the differences are large enough that they might be resolved in future experiments.