INVESTIGATION OF THE ELECTRON-DISTRIBUTION IN BE METAL USING COMPTON-SCATTERING

Directional Compton profiles have been measured in Be metal using 412 keV gamma-rays. Data were collected along 〈0001〉, {Mathematical expression} and {Mathematical expression} in order to investigate the directional dependence of the Compton profile and its Fourier transform. Theories for the momentum density in Be are available which are based on a delocalised model using a pseudopotential wave function, and a localised LCAO approach in which 1 s and 2 s atomic functions are orthogonalised in the crystal. The LCAO calculation comes closest to describing the overall shape of the profile, while the models based on plane waves are able to predict qualitatively the directional dependence. However, none of the available models is able to provide a good description of the momentum density in Be metal. In conclusion, better theoretical calculations are needed, and both charge and momentum densities should be calculated and compared with experiment before the validity of a given theoretical model is judged. © 1979 Springer-Verlag.