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Research Seminar FRIAS Research Focus Quantum Transport - Jochen Blumbergen: Electron flow through bacterial nanowire proteins / David Leitner: Quantum energy flow and localization in molecules

When Jun 30, 2015
from 04:00 PM to 06:15 PM
Where FRIAS, Albertstr. 19, Seminar Room
Contact Name
Contact Phone 0761 203 97362
Attendees universitätsoffen/open to university members
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Abstract Blumberger:

In my talk I will describe our recent efforts to compute the microscopic parameters determining electron transfer in a recently crystallised deca-heme protein (`bacterial nanowire') of the bacterium Shewanella Oneidensis [1], employing fragment orbital density functional theory calculations and molecular dynamics simulation. Comparison between the computed electron flux through the protein, based on sequential electron hopping between the frontier orbitals of the heme groups[2,3], and the experimental solution kinetics on a related protein complex[4] indicates good agreement. We find that electron transport along the heme nanowire is a finely tuned balancing act between the ups and downs on the free energy landscape[5] and heme-heme electronic interactions[3]. Interestingly, at the presence of a finite bias voltage applied to the ends of the protein, calculations based on electron hopping predict currents that are three orders of magnitude lower than measured in AFM experiments [5]. Possible alternative conduction mechanisms that give rise to the high currents observed in experiments will be discussed.

[1] Clarke et al Proc. Natl. Acad. Sci. 108 9384 (2011)
[2] Polizzi et al Faraday Discuss 155 43 (2012)
[3] M. Breuer, K. M. Rosso, J. Blumberger Proc. Natl. Acad. Sci. USA 111 611 (2014).
[4] White et al Proc. Natl. Acad. Sci. USA 110 6346 (2013)
[5] M. Breuer, P. Zarzycki, J. Blumberger, K. M. Rosso, J. Am. Chem. Soc. 134 9868 (2012)
[6] Wigginton et al Geochim. Cosmochim. Acta 71 543 (2007



Abstract Leitner:
Vibrational relaxation and localization in molecules mediate rates of chemical reactions in gas and condensed phase. I shall discuss a quantum mechanical theory for vibrational energy flow in a coupled many-oscillator system, i.e., a large molecule, that yields criteria for localization of vibrational states, which is analogous to Anderson localization in disordered solid state systems. I will also discuss some of the ways in which vibrational relaxation controls the kinetics of simple chemical reactions, and how quantum effects, in particular localization of vibrational states, control vibrational relaxation in molecules and can give rise to long-lived, low-frequency oscillations observed during a variety of photochemical reactions in proteins.