Coherent and incoherent dynamics in excitonic energy transfer: Correlated fluctuations and off-resonance effects
Coherent and incoherent dynamics in excitonic energy transfer: Correlated fluctuations and off-resonance effects
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DOI：
10.1103/physrevb.83.165101
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发表时间：
2011-04-01
影响因子：
3.7
通讯作者：
Nazir, Ahsan
中科院分区：
文献类型：
--
作者：
McCutcheon, Dara P. S.;Nazir, Ahsan
我们研究了一对耦合的两能级系统（施主和受主）与周围环境相互作用的能量转移过程的性质。超越标准的弱耦合方法，我们推导出一个主方程内的极化子表示，允许调查弱和强系统浴耦合，以及可靠的插值这两个限制。有了这个理论，我们就能够探索施主-受主对内能量转移的相干和非相干机制。我们阐明了施主和受主涨落的相关程度、施主-受主能量失配以及环境频率分布的范围对能量转移动力学的影响。在共振的情况下（没有能量失配），我们详细描述了如何从相干到非相干转移动力学的交叉发生随着温度的升高[A。Nazir，Phys. Rev. Lett. 103，146404（2009）]，并且我们还探索了波动相关性如何能够保护能量转移过程中的相干性。我们发现，一个严格的交叉标准是很难定义时，非共振，虽然我们发现定性相似的人口动态的共振情况下，随着温度的升高，而相干人口振荡的幅度也成为抑制与增长的网站能量失配。
We study the nature of the energy transfer process within a pair of coupled two-level systems (donor and acceptor) subject to interactions with the surrounding environment. Going beyond a standard weak-coupling approach, we derive a master equation within the polaron representation that allows for the investigation of both weak and strong system-bath couplings, as well as reliable interpolation between these two limits. With this theory, we are then able to explore both coherent and incoherent regimes of energy transfer within the donor-acceptor pair. We elucidate how the degree of correlation in the donor and acceptor fluctuations, the donor-acceptor energymismatch, and the range of the environment frequency distribution impact upon the energy transfer dynamics. In the resonant case (no energy mismatch) we describe in detail how a crossover from coherent to incoherent transfer dynamics occurs with increasing temperature [A. Nazir, Phys. Rev. Lett. 103, 146404 (2009)], and we also explore how fluctuation correlations are able to protect coherence in the energy transfer process. We show that a strict crossover criterion is harder to define when off-resonance, though we find qualitatively similar population dynamics to the resonant case with increasing temperature, while the amplitude of coherent population oscillations also becomes suppressed with growing site energy mismatch.