  Theoretical calculations under the scheme of WIEN2k computer package had been
performed on the pristine compound LaOFeAs, as well as on LaO1-xFxFeAs. One
factor crucial to the manifestation of superconductivity seems to be fluorine
doping; hence we search for its effect. Paying close attention to Fe d-orbitals
upon doping of F by O, at first, Fe d-orbitals have dz2 symmetry, changing
gradually to something akin to dx2-y2 which seems more prone to conductivity
than the former one. This issue agree with the accepted results happened in the
copper-based high-temperature superconductors.
