Population and coherence dynamics in light harvesting complex II (LH2)

Shu-Hao Yeh, Birck Nanotechnology Center, Purdue University
Jing Zhu, Birck Nanotechnology Center, Purdue University
Sabre Kais, Birck Nanotechnology Center, Purdue University; Qatar Fdn, Qatar Environm & Energy Res Inst

Date of this Version



J. Chem. Phys. 137, 084110 (2012); http://dx.doi.org/10.1063/1.4747622


Copyright (2012) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in J. Chem. Phys. 137, 084110 (2012) and may be found at http://dx.doi.org/10.1063/1.4747622. The following article has been submitted to/accepted by The Journal of Chemical Physics. Copyright (2012) Shu-Hao Yeh, Jing Zhu and Sabre Kais. This article is distributed under a Creative Commons Attribution 3.0 Unported License.


The electronic excitation population and coherence dynamics in the chromophores of the photosynthetic light harvesting complex 2 (LH2) B850 ring from purple bacteria (Rhodopseudomonas acidophila) have been studied theoretically at both physiological and cryogenic temperatures. Similar to the well-studied Fenna-Matthews-Olson (FMO) protein, oscillations of the excitation population and coherence in the site basis are observed in LH2 by using a scaled hierarchical equation of motion approach. However, this oscillation time (300 fs) is much shorter compared to the FMO protein (650 fs) at cryogenic temperature. Both environment and high temperature are found to enhance the propagation speed of the exciton wave packet yet they shorten the coherence time and suppress the oscillation amplitude of coherence and the population. Our calculations show that a long-lived coherence between chromophore electronic excited states can exist in such a noisy biological environment. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4747622]


Nanoscience and Nanotechnology