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

Abstract

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.

A density matrix renormalization group investigation on the electronic states of MnGen−/0/+ (n = 1–3) clusters

“…Because of the high multireference character, a large number of two‐electron detachment processes can be recorded in the spectrum as satellite bands. This feature is obtained in several transition metal‐containing clusters [59–61]. Otherwise, the first ADEs are estimated to decrease from MnGe − (0.94 eV) to FeGe − (0.91 eV), and CoGe − (0.80 eV) [26, 30].…”

Unveiling geometric and electronic structures of NbSi4−/0 clusters and electron detachments of the anionic cluster: A quantum chemical investigation

“…This method has been extensively employed in the study of various clusters, such as NbC 3 −/0 , ScSi n −/0 (n = 4−6), VGe n −/0 (n = 1−4), and VSi 4 −/0 . [18][19][20][21] The integration of theoretical and experimental approaches has yielded promising results in utilizing the CASSCF/CASPT2 method to predict adiabatic detachment energy (ADE) and vertical detachment energy (VDE) values. These predictions have been found to align closely with experimental observations.…”

“…To address these limitations, the multiconfigurational CASSCF/CASPT2 method has gained recognition as a valuable technique for investigating the geometric structure and electronic states of clusters containing transition metals. This method has been extensively employed in the study of various clusters, such as NbC 3 −/0 , ScSi n −/0 ( n = 4−6), VGe n −/0 ( n = 1−4), and VSi 4 −/0 18–21 . The integration of theoretical and experimental approaches has yielded promising results in utilizing the CASSCF/CASPT2 method to predict adiabatic detachment energy (ADE) and vertical detachment energy (VDE) values.…”