Spin‐inversion mechanisms in O2 binding to a model heme compound: A perspective from nonadiabatic wave packet calculations. Issue 29 (25th August 2020)

• Record Type: Journal Article
• Authors: Saito, Kohei; Watabe, Yuya; Miyazaki, Takaaki; Takayanagi, Toshiyuki; Hasegawa, Jun‐ya
• Is Part Of: Journal of computational chemistry. Volume 41:Issue 29(2020)
• Page Start: 2527
• Page End: 2537
• Publication Date: 2020-08-25
• Subjects: Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.26409
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract: Spin‐inversion dynamics in O2 binding to a model heme complex, which consisted of Fe(II)‐porphyrin and imidazole, were studied using nonadiabatic wave packet dynamics calculations. We considered three active nuclear degrees of freedom in the dynamics, including the motions along the Fe–O distance, Fe–O–O angle, and Fe out‐of‐plane distance. Spin‐free potential energy surfaces for the singlet, triplet, quintet, and septet states were developed using density functional theory calculations, and spin–orbit coupling elements were obtained from CASSCF‐level electronic structure calculations. The spin‐inversion mainly occurred between the singlet state and one of the triplet states due to large spin–orbit couplings and the contributions of other states were extremely small. The present quantum dynamics calculations suggested that the narrow crossing region model plays a dominant role in the O2 binding dynamics. In addition, the one‐dimensional Landau–Zener model underestimated the nonadiabatic transition probability. Abstract : Spin‐inversion mechanisms of O2 binding by a model heme compound were studied by quantum nonadiabatic wave packet calculations considering three nuclear degrees of freedom. The potential energy surfaces of the singlet, triplet, quintet, and septet states and their spin–orbit couplings were obtained from density functional theory and CASSCF calculations, respectively. Spin‐inversion dominantly occurred between the singlet state and one of the three triplet spin states and the narrow crossing region model played an important role in the O2 binding dynamics.