Type of Publication:  Journal article 
Author:  Li, Guangqi; Movaghar, Bijan; Nitzan, Abraham; Ratner, Mark A. 
Year of publication:  2013 
Published in:  The Journal of Chemical Physics ; 138 (2013), 4.  044112.  ISSN 00219606.  eISSN 10897690 
Pubmed ID:  23387573 
DOI (citable link):  https://dx.doi.org/10.1063/1.4776230 
Summary: 
We use a onedimensional tight binding model with an impurity site characterized by electronvibration coupling, to describe electron transfer and localization at zero temperature, aiming to examine the process of polaron formation in this system. In particular we focus on comparing a semiclassical approach that describes nuclear motion in this many vibronicstates system on the Ehrenfest dynamics level to a numerically exact fully quantum calculation based on the BoncaTrugman method [J. Bonča and S. A. Trugman, Phys. Rev. Lett.75, 2566 (Year: 1995)]10.1103/PhysRevLett.75.2566. In both approaches, thermal relaxation in the nuclear subspace is implemented in equivalent approximate ways: In the Ehrenfest calculation the uncoupled (to the electronic subsystem) motion of the classical (harmonic) oscillator is simply damped as would be implied by coupling to a Markovian zero temperature bath. In the quantum calculation, thermal relaxation is implemented by augmenting the Liouville equation for the oscillator density matrix with kinetic terms that account for the same relaxation. In both cases we calculate the probability to trap the electron by forming a polaron and the probability that it escapes to infinity. Comparing these calculations, we find that while both result in similar long time yields for these processes, the Ehrenfestdynamics based calculation fails to account for the correct time scale for the polaron formation. This failure results, as usual, from the fact that at the early stage of polaron formation the classical nuclear dynamics takes place on an unphysical average potential surface that reflects the distributed electronic population in the system, while the quantum calculation accounts fully for correlations between the electronic and vibrational subsystems.

Subject (DDC):  530 Physics 
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LI, Guangqi, Bijan MOVAGHAR, Abraham NITZAN, Mark A. RATNER, 2013. Polaron Formation : Ehrenfest dynamics vs. exact results. In: The Journal of Chemical Physics. 138(4), 044112. ISSN 00219606. eISSN 10897690. Available under: doi: 10.1063/1.4776230
@article{Li20130128Polar26563, title={Polaron Formation : Ehrenfest dynamics vs. exact results}, year={2013}, doi={10.1063/1.4776230}, number={4}, volume={138}, issn={00219606}, journal={The Journal of Chemical Physics}, author={Li, Guangqi and Movaghar, Bijan and Nitzan, Abraham and Ratner, Mark A.}, note={Article Number: 044112} }
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