Ab Initio Calculation of Molecular Aggregation Effects: A Coumarin-343 Case Study

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• 作者：Donghyun Lee ; Loren Greenman ; Mohan Sarovar ; K. Birgitta Whaley
• 刊名：Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：October 31, 2013
• 年：2013
• 卷：117
• 期：43
• 页码：11072-11085
• 全文大小：872K
• 年卷期：v.117,no.43(October 31, 2013)
• ISSN：1520-5215

文摘

We present time-dependent density functional theory (TDDFT) calculations for single and dimerized Coumarin-343 molecules to investigate the quantum mechanical effects of chromophore aggregation in extended systems designed to function as a new generation of sensors and light-harvesting devices. Using the single-chromophore results, we describe the construction of effective Hamiltonians to predict the excitonic properties of aggregate systems. We compare the electronic coupling properties predicted by such effective Hamiltonians to those obtained from TDDFT calculations of dimers and to the coupling predicted by the transition density cube (TDC) method. We determine the accuracy of the dipole鈥揹ipole approximation and TDC with respect to the separation distance and orientation of the dimers. In particular, we investigate the effects of including Coulomb coupling terms ignored in the typical tight-binding effective Hamiltonian. We also examine effects of orbital relaxation which cannot be captured by either of these models.