Mixed quantum classical simulations of electronic excitation energy transfer: The pheophorbide-a DAB dendrimer P₄ in solution

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• 作者：Hui Zhu ; Volkhard May ; Beate Rö ; der
• 关键词：Electronic excitation energy transfer ; Chromophore complexes ; Frenkel-excitons ; Mixed quantum classical methodology ; MD simulations
• 刊名：Chemical Physics
• 出版年：2008
• 出版时间：3 July 2008
• 年：2008
• 卷：351
• 期：1-3
• 页码：117-128
• 全文大小：905 K

文摘

Photoinduced electronic excitation energy transfer in chromophore complexes is studied by utilizing a mixed quantum classical methodology. Electronic excitations are characterized by a Frenkel-exciton model and treated quantum mechanically while all nuclear coordinates are described classically finally by carrying out room-temperature MD simulations. The theory is applied to the chromophore complex P₄ dissolved in ethanol. P₄ is formed by a butanediamine dendrimer to which four pheophorbide-a molecules have been covalently linked. The c608cd74abe"" title=""Click to view the MathML source"" alt=""Click to view the MathML source"">P₄ excited electronic states have to be described in an improved exciton model which accounts for charge distributions in the chromophores electronic ground and excited state. It also includes a correct description of the excitonic coupling among different chromophores based on the introduction of atomic centered transition charges. Excitation energy transfer is discussed in using adiabatic exciton states as well as a full solution of the time-dependent Schrödinger equation. To underline the effect of strong excitonic coupling emphasis is also placed on MD runs where two chromophores are positioned close together. Relations are discussed to the standard treatment of exciton dynamics in using the density matrix theory as well as by introducing rate equations based on rate expressions according to Förster.