SCIENCE AT THE EDGE – INTERDISACIPLINARY PHYSICS

11:30 a.m., Room 1400 Biomedical Physical Sciences Bldg.

Nonadiabatic Transition State Theory: Application to Intersystem Crossings in the Active Sites of Metal-Sulfur Proteins

Sergey A. Varganov

University of Nevada, Reno

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 basic NA-TST steps including calculations of the transition probability and coupling between electronic states, a search for the minimum energy crossing point, and computations of the densities of states and partition functions will be discussed. The shortcomings of the spin-diabatic version of NA-TST related to ill-defined state coupling and state counting will be highlighted. The application of NA-TST to intersystem crossings in the active sites of the metal-sulfur proteins [NiFe]-hydrogenase, rubredoxin and Fe₂S₂-ferredoxin will be demonstrated. We speculate that spin-forbidden nonadiabatic reaction mechanisms could play an important role in electron transfer and enzymatic catalysis involving these metal-sulfur proteins.

HOST:  Benjamin Levine< Chemistry

Carlo Piermarocchi< Physics & Astronomy

Shawna Prater / Secretary

Astrophysics Group

Michigan State University

567 Wilson Road, Room 3261

Biomedical Physical Sciences Bldg

East Lansing, MI 48824-2320

Ph: (517) 884-5601 Fax (517) 432-8802

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