Fermi-surface and electron correlation in A1 studied by Compton scattering

We have studied the electron-momentum density distribution in Al using the coincidence as well as the conventional high-resolution Compton scattering technique. In order to interpret the results, corresponding band theory based computations of the electron momentum density (EMD) and the Compton profiles (CPs) have been carried out. Our focus here is on determining the size of the break ZF in the EMD at the Fermi momentum. For this purpose, differences between measurements and theoretical predictions are analyzed in terms of a simple model for describing electron correlation effects which are missing from the independent particle band theory framework; the model involves ZF as the only adjustable parameter. A good fit with the coincidence measurements is obtained for ZF of about 0.7, while the CP data yields ZF = 0.7 to 0.8. This study suggests that, in sharp contrast to the case of Li where recent high-resolution Compton work indicates ZF≈0, the standard picture of the interacting electron gas is substantially correct in Al.