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

Abstract

We present time-dependent density functional theory (TDDFT) calculations for single and dimerized Coumarin-343 molecules in order 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-dipole 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.

References in corpus (2)

• Quantum entanglement in photosynthetic light harvesting complexes
• Design principles and fundamental trade-offs in biomimetic light harvesting

Cited by in corpus (3)

• Benchmarking calculations of excitonic couplings between bacteriochlorophylls
• How two-dimensional brick layer J-aggregates differ from linear ones: excitonic properties and line broadening mechanisms
• Molecular Mechanics Simulations and Improved Tight-binding Hamiltonians for Artificial Light Harvesting Systems: Predicting Geometric Distributions, Disorder, and Spectroscopy of Chromophores in a Protein Environment