Nonadiabatic transition state theory: Application to intersystem crossings in the active sites of metal‐sulfur proteins. Issue 10 (20th March 2016)

• Record Type: Journal Article
• Authors: Lykhin, Aleksandr O.; Kaliakin, Danil S.; dePolo, Gwen E.; Kuzubov, Alexander A.; Varganov, Sergey A.
• Other Names: Levine Benjamin G. guestEditor.; Varganov Sergey A. guestEditor.
• Is Part Of: International journal of quantum chemistry. Volume 116:Issue 10(2016)
• Page Start: 750
• Page End: 761
• Publication Date: 2016-03-20
• Subjects: intersystem crossing -- nonadiabatic transition state theory -- metal‐sulfur proteins; Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.25124
• Languages: English
• ISSNs: 0020-7608

Abstract

Abstract : Nonadiabatic transition state theory (NA‐TST) is a powerful tool to investigate the nonradiative transitions between electronic states with different spin multiplicities. The statistical nature of NA‐TST provides an elegant and computationally inexpensive way to calculate the rate constants for intersystem crossings, spin‐forbidden reactions, and spin‐crossovers in large complex systems. The relations between the microcanonical and canonical versions of NA‐TST and the traditional transition state theory are shown, followed by a review of the basic steps in a typical NA‐TST rate constant calculation. These steps include evaluations of the transition probability and coupling between electronic states with different spin multiplicities, a search for the minimum energy crossing point (MECP), and computing the densities of states and partition functions for the reactant and MECP structures. The shortcomings of the spin‐diabatic version of NA‐TST related to ill‐defined state coupling and state counting are highlighted. In three examples, we demonstrate the application of NA‐TST to intersystem crossings in the active sites of metal‐sulfur proteins focusing on [NiFe]‐hydrogenase, rubredoxin, and Fe2 S2 ‐ferredoxin. © 2016 Wiley Periodicals, Inc. Abstract : Nonadiabatic transition state theory (NA‐TST) provides an efficient statistical method for calculating the microcanonical and canonical rate constants of spin‐forbidden processes in large complex systems. This review discusses the steps of the NA‐TST rate calculations including the evaluation of transition probability and spin‐orbit coupling between spin‐diabatic states, as well as the computation of density of rovibrational states and search for minimum energy crossing point.