  We report a comparison study of LaOFeP and LaOFeAs, two parent compounds of
recently discovered iron-pnictide superconductors, using angle-resolved
photoemission spectroscopy. Both systems exhibit some common features that are
very different from well-studied cuprates. In addition, important differences
have also been observed between these two ferrooxypnictides. For LaOFeP,
quantitative agreement can be found between our photoemission data and the LDA
band structure calculations, suggesting that a weak coupling approach based on
an itinerant ground state may be more appropriate for understanding this new
superconducting compound. In contrast, the agreement between LDA calculations
and experiments in LaOFeAs is relatively poor, as highlighted by the unexpected
Fermi surface topology around (pi,pi). Further investigations are required for
a comprehensive understanding of the electronic structure of LaOFeAs and
related compounds.
