Methodological CASPT2 study of the valence excited states of an iron-porphyrin complex

作者：Ben Amor Nadia^*; Soupart Adrien; Heitz Marie Catherine^*

来源：Journal of Molecular Modeling, 2017, 23(2): 53.

DOI：10.1007/s00894-017-3226-y

• CASSCF
• IPEA shift
• Iron-porphyrin
• Metallo-porphyrin
• MS-CASPT2

The singlet valence excited states of an ironporphyrin-pyrazine-carbonyl complex are investigated up to the Soret band (about 3 eV) using multi-state complete active space with perturbation at the second order (MS-CASPT2). This complex is a model for the active site of carboxy-hemoglobin/ myoglobin. The spectrum of the excited states is rather dense, comprising states of different nature: d ->pi* transitions, d -> d states, pi ->pi* excitations of the porphyrin, and doubly excited states involving simultaneous intra-porphyrin pi ->pi* and d -> d transitions. Specific features of the MS-CASPT2 method are investigated. The effect of varying the number of roots in the state average calculation is quantified as well as the consequence of targeted modifications of the active space. The effect of inclusion of standard ionization potentialelectron affinity (IPEA) shift in the perturbation treatment is also investigated.

• 出版日期2017-2