On the Electronic and Geometric Structures of FeO2–/0 and the Assignment of the Anion Photoelectron Spectrum

Ground and Low-Lying Excited States of NbC3-/0 Clusters: Assignment of the Anion Photoelectron Spectra from Multiconfigurational Calculations

The BP86 DFT, CCSD(T), and CASPT2 methods were employed to study the low-lying states of NbC₃^-/0 clusters. The anionic and neutral ground states were determined to be the ¹A₁ and 1²A₁ of the cyclic-NbC₃^-/0 isomers. All bands in the photoelectron spectra of the NbC₃^- cluster were interpreted based on electron detachment processes from the ¹A₁ of the cyclic-NbC₃^- isomer. The X, A, B, and C bands in the spectra are, respectively, ascribed to the transitions from ¹A₁ to the 1²A₁, ²B₁, 2²A₁, and ²B₂ states. The wave function of the initial ¹A₁ anionic state exhibits a pronounced multireference character that plays to some extent a role in the ¹A₁ → 1²A₁ and the ¹A₁ → 2²A₁ ionizations. Only the ¹A₁ → ²B₂ transition appears as a clear one-electron detachment process. The Franck-Condon factor simulations for the ¹A₁ → 1²A₁ and ¹A₁ → ²B₁ transitions are consistent with the observed vibrational progressions of the X and A bands in the spectra.

The Electronic Structures of CoGe n-/0 ( n = 1-3) Clusters from Multiconfigurational CASSCF/CASPT2 and RASSCF/RASPT2 Calculations

Density functional theory and multiconfigurational CASPT2 and RASPT2 methods are employed to investigate the low-lying states of CoGe _n^-/0 ( n = 1-3) clusters. With the RASPT2 approach, the active space is extended to 14 orbitals for CoGe^-/0, 17 orbitals for CoGe₂^-/0, and 20 orbitals for CoGe₃^-/0. These active spaces include the 3d, 4s, and 4d of Co and 4p of Ge. The 4d of Co is incorporated into these active spaces in order to account for the important double-shell effect of Co. The structural parameters, vibrational frequencies, and relative energies of the low-lying states of CoGe _n^-/0 ( n = 1-3) are reported. The ground states of CoGe _n^- ( n = 1-3) are computed to be ³Φ of linear CoGe^-, ³B₁ of cyclic CoGe₂^-, and ³B₁ of cyclic CoGe₃^- isomer. The ground states of the neutral clusters are calculated to be ²Δ of linear CoGe, ⁴B₁ of cyclic CoGe₂, and ⁴A″ of tetrahedral CoGe₃ isomer. The calculated adiabatic and vertical detachment energies of the anionic ground states are in agreement with the experimental values as observed in the 266 nm anion photoelectron spectra.