Simulating Excitation Energy Transfer Dynamics and Linear Optical Spectra with the Small Polaron Theory
Date Issued
2014
Date
2014
Author(s)
Chang, Hung-Tzu
Abstract
Excitation energy transfer is crucial to the efficiency of solar energy harvesting. The small polaron quantum master equation (SPQME) is a promising approach to describe coherent excitation energy transfer dynamics in complex molecular systems and exceeds the limits of conventional F"orster and Redfield theories. Here we first demonstrate that the polaronic Markovian energy transfer rate presents a unified framework to elucidate the behaviour and mechanisms of exciton transfer. From the polaron rate expression we elicit two major factors affecting the exciton transfer rate: the multitude of energy-dissipation pathways that facilitates exciton transfer and the fluctuation-induced localization that causes exciton self-trapping. Second, we conduct a comprehensive benchmark of the small polaron population dynamics comparing with numerically-exact quasi-adiabatic path integral calculations, where we discover that the small polaron theory is applicable in a wide parameter range. Moreover, we show that the performance of SPQME depends strongly upon the extent of exciton delocalization and polaron formation rate. Therein we propose a criterion to assess the regime of applicability for SPQME. Finally, we present our newly developed methods for computation of absorption and emission spectra within the polaron framework so as to facilitate practical modeling of light-harvesting systems using the small polaron theory.
Subjects
小極化子理論
激發態能量傳遞
密度矩陣理論
量子主方程
馬可夫能量傳輸速率
吸收光譜
放射光譜
Type
thesis
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