Ab initio electronic and optical spectra of free-base porphyrins: The role of electronic correlation.

European Theoretical Spectroscopy Facility (ETSF), University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy.
The Journal of Chemical Physics (Impact Factor: 3.12). 09/2009; 131(8):084102. DOI: 10.1063/1.3204938
Source: PubMed

ABSTRACT We present a theoretical investigation of electronic and optical properties of free-base porphyrins based on density functional theory and many-body perturbation theory. The electronic levels of free-base porphine (H(2)P) and its phenyl derivative, free-base tetraphenylporphyrin (H(2)TPP) are calculated using the ab initio GW approximation for the self-energy. The approach is found to yield results that compare favorably with the available photoemission spectra. The excitonic nature of the optical peaks is revealed by solving the Bethe-Salpeter equation, which provides an accurate description of the experimental absorption spectra. The lowest triplet transition energies are in good agreement with the measured values.

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