Our calcns. Excited states of donor-acceptor dimers were studied using many-body Green's functions theory within the GW approxn. For prototypical small-mol. Application to larger systems is possible and allowed one to analyze energy levels and binding energies of excitons in representative dimers of di-cyanovinyl-substituted quarter-thiophene and fullerene, a donor-acceptor pair used in state of the art org.
In these dimers, the transition from Frenkel to charge transfer excitons is endothermic and the binding energy of charge transfer excitons is still of the order of 1. Hence, even such an accurate dimer-based description does not yield internal energetics favorable for the generation of free charges either by thermal energy or an external elec.
For qual. Many-body perturbation theory in the GW approxn. Here, we assess the performance of these methods for benzene, pyridine, and the diazines. The quasiparticle spectra are compared to photoemission spectroscopy PES expts. We find that the accuracy of the calcd.
The GW-technol. We present the formalism and implementation of GW adapted for std. Our implementation is tested using a typical set of mols. We find that already after the first iteration of the self-consistency cycle, G0W0, the deviations of quasi-particle energies from exptl.
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Also, we confirm that even on this level of approxn. Excited states of dicyanovinyl-substituted oligothiophenes are studied using many-body Green's functions theory within the GW approxn. By varying the no. The full dynamically screened Bethe-Salpeter equation yields absorption and emission energies in agreement with exptl. The authors analyze excitations in oligomers up to a length of 5 nm and find that for both materials the absorption energy practically sats.
In the bimol. The high CT binding energy of the order of 2 eV results from the lack of an explicit mol. The authors also identify a globally unbound charge transfer state with a more delocalized hole at higher energy while still within the absorption spectrum, which opens another potential pathway for charge sepn.
These results support that the higher power conversion efficiency obsd. Electronic excitations in dil. Oligomers up to a length of 7. After equilibration using atomistic mol. Optical absorption properties are calcd. The model allows to differentiate the influence of oligomer conformation induced by the solvation from electronic effects related to local elec.
It is found that the electronic environment contributions are negligible compared to the conformational dynamics of the conjugated PPE. An anal. Royal Society of Chemistry. A combination of classical mol. DFT calcns.
Many-body Green's function theory within the GW approxn. This allows for the calcn. American Institute of Physics. We study within the perturbative many-body GW Green's function G and the screened Coulomb interaction W and Bethe-Salpeter approach the low lying singlet charge-transfer excitations in mol. The present results pave the way to the study of photoinduced charge transfer processes in photovoltaic devices with a parameter-free ab initio approach showing equiv.
The nature of low energy optical excitations, or excitons, in org. Excitons in solid pentacene, a prototypical org. Using first-principles calcns.
The authors show that several low-energy singlet excitations are characterized by a weak overlap between electron and hole and an av. Royal Society. Many-body Green's function perturbation theories, such as the GW and Bethe-Salpeter formalisms, are starting to be routinely applied to study charged and neutral electronic excitations in mol. In parallel, d. We give an overview and compare these approaches with examples drawn from the study of gas phase org.
The perspectives and challenges that many-body perturbation theory is facing, such as the role of self-consistency, the calcn.
We perform benchmark calcns. We show that Bethe-Salpeter calcns. Starting from the popular PBE0 hybrid functional significantly improves the results even though this leads to an av. It is shown, however, that a simple self-consistent scheme at the GW level, with an update of the quasiparticle energies, not only leads to a much better agreement with ref. On av. We discuss an efficient approach to excited electronic states within ab initio many-body perturbation theory MBPT.
Quasiparticle corrections to d. They are evaluated as a small perturbation to the d.ergo-docs.therefore.ca/4326.php
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The dielec. The approach also describes electron-hole interaction.
The resulting electronic and optical spectra are slightly less accurate but much faster to calc. To calc. FSD is derived from the eigenstate energies and populations, and therefore the FSD couplings contain all contributions in the Hamiltonian as well as the potential overlap effect. In the present work, two series of mols. TET study. The TET coupling results are largely similar to those from the previously developed direct coupling scheme, with FSD being easier and more flexible in use. On the other hand, the Dexter's exchange integral value, a quantity that is often used as an approx.
To test the FSD for intramol.
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TET, we have calcd. Our estd. The FSD method can be used for both intermol. TET, regardless of their symmetry. This general applicability is an improvement over most existing methodologies. Electronic considerations of direct and through-configuration exciton resonance interactions. The electronic interactions which promote singlet-singlet and triplet-triplet electronic excitation energy transfer EET are investigated in detail. Introduction of the Mulliken approxn. The origins of "Dexter-type" energy transfer are thus shown to be quite different from that originally outlined.
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