Electronic spectrum of porphyrins. CS INDO CI study

The electronic spectra of porphin, chlorin and their magnesium derivatives have been studied quantum-mechanicallywith the CS INDO CI method. Both the SOPS, and T,-T, one-photon absorption spectra have been analyzed togetherwith the correlation effects. The main result regards the T-T spectrum of porphin. To obtain a correct description of thecomplete spectrum it is necessary to take account of the correlation effects. Gouterman’s model of four orbitals is toosimple to describe the region of the Soret band.