title: Electronically excited states of cob(ii)alamin: insights from CASSCF/XMCQDPT2 and TD-DFT calculations.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, USA. pawel@louisville.edu.
authors.forename: Brady D
authors.initials: BD
authors.lastname: Garabato
authors.affiliation: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, USA. pawel@louisville.edu and Pacific Northwest National Laboratory, P.O. Box 999, MS K2-57, Richland, WA 99352, USA.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Kumar
authors.affiliation: Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Lodowski
authors.affiliation: Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, Szkolna 9, PL-40 006 Katowice, Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Jaworska
authors.affiliation: Department of Chemistry, University of Louisville, 2320 South Brook Street, Louisville, Kentucky 40292, USA. pawel@louisville.edu and Visiting Professor at the Department of Food Sciences, Medical University of Gdansk, Al. Gen. J. Hallera 107, 80-416 Gdansk, Poland.
authors.forename: Pawel M
authors.initials: PM
authors.lastname: Kozlowski
mesh_terms: D004583:Electrons; D015394:Molecular Structure; D011789:Quantum Theory; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: C097751:cob(II)alamin; D014805:Vitamin B 12