Ab initio molecular orbital calculation of fe‐porphine with a double zeta basis set

An ab initio LCAO SCF MO calculation was performed on planar Fe‐porphine with a double zeta basis set consisting of 300 CGTO 's. SCF wave functions of several states of Fe‐porphine and its cation were obtained. The net charge of Fe is in the range of 1.39 to 1.53. The highest occupied orbital is ascertained to be a pure porphine π‐ MO , 1 a 1 u . The calculated ionization potentials of the two highest occupied orbitals, 1 a 1 u and 5 a 2 u are 5.98 and 6.43 eV, respectively. They are in good agreement with experiments. The role of the porphine macrocycle on the oxidation of Fe is discussed in terms of gross atomic populations and with contour maps of the density difference.