  The construction of a multi-channel vector spin polarimeter requires the
development of a new detector type, which works as a spin polarizing mirror
with high reflectivity and asymmetry properties to guarantee for a high figure
of merit. Technical realizations are found by spin polarized electron
scattering from a surface at low energies. A very promising candidate for such
a detector suitable material consists of an oxygen passivated iron surface, as
for example a Fe(001)-p(1x1)-O surface. We investigate in detail the electronic
structure of this adsorbate system and calculate the corresponding
spin-polarized low-energy electron scattering. Our theoretical study is based
on the fully relativistic SPRKKR-method in the framework of density functional
theory. Furthermore, we use the local spin-density approximation in combination
with dynamical mean field theory to determine the electronic structure of
Fe(001)-p(1x1)-O and demonstrate that a significant impact of correlation
effects occurs in the calculated figure of merit.
