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Center for Nonlinear Studies |
A practical method to obtain CT energies for systems containing 100-400 atoms is developed and refined within the density functional theory. A benchmark of the method showed a mean absolute deviation from experimentally determined CT energies of 0.09 eV. Using this method, we have studied the charge transfer states of various organic donor-acceptor systems used in laboratory, such as the porphyrin-fullerene and phthalocyanine-fullerene donor-acceptor supramolecular pairs. In addition, we undertake a combined ground- and excited-state electronic structure study of various conformational configurations of a 207-atom carotene-porphyrin-C60 triad, where its ability to generate a large dipole moment (~160 D) has generated great interest for application in photovoltaic devices. Solvation effects are estimated for several systems by using a combined Quantum Mechanics and Molecular Mechanics (QM/MM) approach. Lastly, using Molecular Dynamics (MD) simulations, we explore the morphology of binary monolayers and stacked multi-layers of organic conjugates adsorbed on metal substrates in order to determine which donor-acceptor pairs are better suited for generating supramolecular architectures capable of forming orderly and periodic domains of CT complexes.