Abstract
Directional Compton profiles (CP’s) of were measured for (11)12 directions of the momentum transfer q with (0.14) 0.16 a.u. units: momentum space resolution using synchrotron x rays, monochromatized to (31) 59 keV (values in brackets refer to The total experimental valence electron CP’s, their second derivatives, and the associated directional differences were compared with the corresponding Korringa-Kohn-Rostoker–coherent-potential-approximation–local-density-approximation (KKR–CPA–LDA) computations. Discrepancies between measurements and calculations are partly traced back to an inadequate treatment of electron correlation effects within the LDA framework. The three-dimensional (3D) valence-electron momentum density, ρ(p), as well as the 3D occupation number density were reconstructed from experimental data using the Fourier-Bessel method. The reconstructed ρ(p)’s exhibit evidence of higher momentum components due to 110 umklapp processes, whose variations with x are in reasonable agreement with the KKR-CPA calculations. The experimental ’s provide a direct measure of the Fermi-surface anisotropy and show the presence of necks on the 110 Brillouin-zone boundaries for in good accord with 2D positron annihilation experiments.
- Received 4 January 1999
DOI:https://doi.org/10.1103/PhysRevB.60.7099
©1999 American Physical Society