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Cyclic and Linear NiO 2 : A Multireference Configuration Interaction Study

2012; American Chemical Society; Volume: 116; Issue: 36 Linguagem: Inglês

10.1021/jp306421x

1520-5215

Olaf Hübner, Hans‐Jörg Himmel,

Catalysis and Oxidation Reactions

Linear (ONiO) and triangular (Ni(O2)) isomers of NiO2 are investigated by multiconfiguration self-consistent field (MCSCF) and multireference configuration interaction (MRCI) calculations. For ONiO, the ground electronic term is a 1Σg+ term. The lower-lying excited terms are 3Πg, 1Πg, and 5Πu at relative energies of 0.55, 0.95, and 1.20 eV, respectively. For Ni(O2), the ground electronic term is a 1A1 term with an energy of 1.53 eV with respect to the ONiO ground state. Lower-lying excited terms are 5B2, 5A1, and 3B2 at 0.58, 0.62, and 0.73 eV with respect to the 1A1 state, respectively. A transition structure between the ground states of both isomers has been located with an energy of 2.76 eV above the ONiO ground state. For the fragmentation Ni(O2) → Ni + O2 the (electronic) reaction energy is estimated to 1.15 eV. The wave function based results demonstrate the failure of previous density functional investigations and emphasize the importance of a multireference treatment.