Compton scattering studies of the valence electron density distribution in GaAs

Directional Compton profiles have been measured along the (100), (110), (111), (112) and (221) crystallographic axes in GaAs using 412 keV and 59.54 keV gamma -radiation from ¹⁹⁸Au and ²⁴¹Am radioisotope sources, respectively. The results have been compared with the prediction of a pseudopotential calculation both in momentum space and in position space. The pseudopotential approach predicts the anisotropy of the valence electron distribution and is consistent with an increase in the ionic bond character compared with Ge. On the other hand, the total electron distributions are not well described due to the omission of core orthogonalisation terms.