Theoretical study of the electronic spectrum of magnesium-porphyrin

作者：Mercedes Rubio, Björn Olof Roos, Luis Serrano‐Andrés, Manuela Merchán · 发表于：The Journal of Chemical Physics · 年份：1999 · DOI：10.1063/1.478624 · 被引用次数：80 · 研究领域：Advanced Chemical Physics Studies、Porphyrin and Phthalocyanine Chemistry、Molecular Junctions and Nanostructures

Multiconfigurational self-consistent field (SCF) and second order perturbation methods have been used to study the electronic spectrum of magnesium-porphyrin (MgP). An extended ANO-type basis set including polarization functions on all heavy atoms has been used. Four allowed singlet states of E1u symmetry have been computed and in addition a number of forbidden transitions and a few triplet states. The results lead to a consistent interpretation of the electronic spectrum, where the Q band contains one transition, the B band two, and the N band one. The computed transition energies are consistently between 0.1 and 0.5 too low compared to the measured band maxima. The source of the discrepancy is the approximate treatment of dynamic correlation (second order perturbation theory), limitations in the basis set and the fact that all measurements have been made on substituted magnesium porphyrins.