  We discuss an efficiency of various band structure algorithms in determining
the Fermi surface (FS) of the paramagnetic ErGa3. The linear muffin-tin orbital
(LMTO) in the atomic sphere approximation (ASA) method and three full potential
(FP) codes: FP-LMTO, FP linear augmented plane wave (FLAPW), and FP local
orbitals (FPLO) methods are employed. Results are compared with
electron-positron (e-p) momentum densities reconstructed from two dimensional
angular correlation of annihilation radiation (2D ACAR). Unexpectedly, none of
used modern FP codes is able to give satisfying description of the experimental
data that are in perfect agreement with LMTO-ASA results. We suspect that it
can be connected with a different choice of the linearization energy.
