Electronically excited states of cob(ii)alamin: insights from CASSCF/XMCQDPT2 and TD-DFT calculations

The low-lying excited states of cob(ii)alamin were investigated using time-dependent density functional theory (TD-DFT). The performance of TD-DFT calculations was further evaluated using CASSCF/XMCQDPT2, where both four-coordinate and five-coordinate models of cob(ii)alamin were considered. Depende...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2016-02, Vol.18 (6), p.4513-4526
Main Authors: Garabato, Brady D, Kumar, Neeraj, Lodowski, Piotr, Jaworska, Maria, Kozlowski, Pawel M
Format: Article
Language:English
Subjects:
Benchmarks
Density functional theory
Electronic structure
Electrons
Grounds
Mathematical models
Molecular Structure
Orbitals
Physical chemistry
Quantum Theory
Time dependence
Vitamin B 12 - analogs & derivatives
Vitamin B 12 - chemistry
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Summary:The low-lying excited states of cob(ii)alamin were investigated using time-dependent density functional theory (TD-DFT). The performance of TD-DFT calculations was further evaluated using CASSCF/XMCQDPT2, where both four-coordinate and five-coordinate models of cob(ii)alamin were considered. Dependence of electronic structure on the axial base was then investigated using TD-DFT. Consistent with previous benchmarks, the BP86 functional provides a reliable description of the electronically excited states. It was found that the dyz + π → dz(2) character of the D1 state increases with respect to the axial base distance, corresponding to a lowering in energy of anti-bonding dz(2) orbitals, leading to near a degeneracy between the ground, and D1 states in the base-off form.
ISSN:1463-9076
1463-9084
DOI:10.1039/c5cp06439b