Directional Compton profiles and the electron density distribution in iron

The (100), (110) and (111) directional Compton profiles and their reciprocal form factors (B functions) have been deduced from Compton scattering measurements on single crystal slices of iron with 198 Au 412 keV gamma radiation. The accuracy of the individual profiles is sufficient not only to detect the small asphericity in the electron momentum density but also to discriminate between APW and LCAO band-structure models. In general terms the LCAO calculations with a Gaussian basis describe the momentum density better, although, in common with studies of other transition metals, the asphericity is still overestimated. Inspection of the reciprocal form factor reveals aspects of the density distribution not adequately by either model.