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Franck–Condon and Jahn–Teller effects in the E ′ 1 state of (CO) 2− 5 molecule. Resonance and preresonance Raman study in terms of time‐dependent density functional theory: New insight into an old story
Author(s) -
Makowski Marcin,
Pawlikowski Marek T.
Publication year - 2005
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.20519
Subject(s) - chemistry , density functional theory , jahn–teller effect , raman spectroscopy , resonance (particle physics) , absorption (acoustics) , molecule , ring (chemistry) , absorption spectroscopy , computational chemistry , atomic physics , ion , quantum mechanics , materials science , physics , organic chemistry , composite material
Franck–Condon and Jahn–Teller effects in the E ′ 1state of the croconate dianion are studied in terms of time‐dependent density functional theory (TD‐DFT) at the B3LYP/aug‐cc‐pVDZ and BP86/aug‐cc‐pVDZ levels. The results of these treatments are then used to discuss the empirical absorption, preresonance, and resonance Raman spectra associated with A ′ 1→ E ′ 1transition in the croconate dianion. In agreement with the experiment, the computations done at the B3LYP/aug‐cc‐pVDZ level of approximation predict substantial Jahn–Teller and Franck–Condon activities of ν 2 ( a ′ 1 ) = 607 cm −1 (ring‐breathing) and ν 11 ( e ′ 2 ) = 526 cm −1 (ring‐bending) modes in the lowest‐energy E ′ 1state of the croconate ion. The activities of the other e ′ 2 ‐ and a ′ 1 ‐symmetry modes were found to be quite modest. It is shown that the sizable activities of ν 2 ( a ′ 1 ) and ν 11 ( e ′ 2 ) modes lead to Bactrian‐like structure in the absorption corresponding to the A ′ 1→ E ′ 1transition. Taking into account the consistencies between the electronic absorption and Raman experiments, we can convincingly argue that the double‐band shape experimentally observed in the absorption of the croconate dianion cannot be attributed to solute–solvent interactions, as was recently proposed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005