  We calculate electronic structures of a high-Tc iron-based superconductor
Sr2VFeAsO3 by LDA+U method. We assume a checker-board antiferromagnetic order
on blocking layers including vanadium and strong correlation in d-orbits of
vanadium through the Hubbard U. While the standard LDA brings about metallic
blocking layers and complicated Fermi surface as in the previous literatures,
our calculation changes the blocking layer into insulating one and the Fermi
surface becomes quite similar to those of other iron-based superconductors.
Moreover, the appearance of the insulating blocking layers predicts high
anisotropy on quasi-particle transports and new types of intrinsic Josephson
effects.
