  A new method (NM) for filtering three-dimensional reconstructed densities is
proposed. The algorithm is tested with simulated spectra and employed to study
the electronic structure of the rare-earth compound LaB6. For this system,
momentum densities are reconstructed from theoretical and experimental
two-dimensional angular correlation of electron-positron annihilation radiation
(2D ACAR) spectra. The experimental results are in good agreement with the band
structure calculated with the full-potential linearized augmented-plane-wave
(FLAPW) method within the local-density approximation (LDA), apart from the
detection of small electron pockets in the 15th band. It is also shown that,
unlike the electron-positron enhancement, the electron-electron correlations
affect noticeably the momentum density.
