Fermi-surface and electron correlation in Al 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 bas ed computations of the electron momentum density (EMD) and the Compton prof iles (CPs) have been carried out. Our focus here is on determining the size of the break Z(F) in the EMD at the Fermi momentum. For this purpose, diff erences between measurements and theoretical predictions are analyzed in te rms of a simple model for describing electron correlation effects which are missing from the independent particle band theory framework; the model inv olves Z(F) as the only adjustable parameter. A good fit with the coincidenc e measurements is obtained for Z(F) of about 0.7, while the CP data yields Z(F) = 0.7 to 0.8. This study suggests that, in sharp contrast to the case of Li where recent high-resolution Compton work indicates Z(F) approximate to 0, the standard picture of the interacting electron gas is substantially correct in Al. (C) 2000 Elsevier Science Ltd. All rights reserved.