6533b858fe1ef96bd12b6c94
RESEARCH PRODUCT
Interpretation of the electronic absorption spectrum of free base porphin by using multiconfigurational second-order perturbation theory
Mercedes RubioLuis Serrano-andrésBjörn O. RoosManuela Merchánsubject
chemistry.chemical_compoundValence (chemistry)Absorption spectroscopychemistryAb initio quantum chemistry methodsExcited stateDegenerate energy levelsGeneral Physics and AstronomyPhysical and Theoretical ChemistryAtomic physicsBasis setSpectral linePorphindescription
Abstract Multiconfigurational second-order perturbation (CASPT2) calculations have been performed on the low-lying optically allowed valence excited states of the free base porphin molecule in order to assign the four lowest bands of the spectrum. The low-lying triplet states have also been characterized. A basis set of the atomic natural orbital type of split-valence plus polarization quality for first-row atoms has been employed. Polarization functions are important for an accurate description of the transitions. These CASPT2 results provide a consistent picture of the experimental spectrum. Each band of the spectrum up to 4.5 eV is composed of a pair of states, which become degenerate in the spectra of metal–porphyrins. Our interpretation deviates from assignments based on other types of ab initio calculations.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1998-10-01 | Chemical Physics Letters |