  Orbital polarization and electronic correlation are two essential aspects in
understanding the normal state and superconducting properties of multiorbital
FeAs-based superconductors. In this Letter, we present a systematical study on
the orbital polarization of iron pnictides from weak to strong Coulomb
correlations within the KRSB approach. The magnetic phase diagram of the
two-orbital model for LaFeAsO clearly shows that the striped antiferromagnetic
metallic phase with considerable orbital polarization exists over a wide doping
range. The reversal of the orbital polarization occurs in the intermediate
correlation regime.A small crystal field splitting enhances the orbital density
wave order.
