A theoretical study of the electronic spectrum of bithiophene

Rubio, Mercedes; Merchán, Manuela; Ortı́, Enrique; Roos, Björn O.

doi:10.1063/1.468587

Cited by 49 publications

(55 citation statements)

References 29 publications

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“…It is perhaps the reason that there have been only few theoretical studies dealing with the excited states of bithiophene. Rubio et al [25,26] applied the CASSCF/CASPT2 methodology to study the lowest p-p* excitations of 2T. They reported a pair of B u states of similar energies (3.88 and 4.15 eV) and a third state of considerably higher energy (5.53 eV).…”

Section: Introductionmentioning

confidence: 99%

The elusive excited states of bithiophene: a CASPT2 detective story

Andrzejak

Witek

2011

Theor Chem Acc

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Section: Introductionmentioning

confidence: 99%

The elusive excited states of bithiophene: a CASPT2 detective story

Andrzejak

Witek

2011

Theor Chem Acc

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“…Various forms of optical spectroscopy together with theoretical interpretations have provided us with the location of the lowest-energy singlet excitations, [13][14][15][16][17][18][19][20][21][22][23][24][25][26] as well as in some cases the triplets. 27 As we will discuss below, the lowestenergy singlet excitations show a 1/N-like dependence ͑with N the number of rings͒ on the oligomer length, whereas the lowest triplets are considerably lower in energy.…”

Section: Introductionmentioning

confidence: 99%

Density-functional study of the evolution of the electronic structure of oligomers of thiophene: Towards a model Hamiltonian

et al. 2001

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Density-functional study of the evolution of the electronic structure of oligomers of thiophene Telesca, R.; Bolink, H.; Yunoki, S.; Hadziioannou, G.; Duijnen, P.Th. van; Snijders, J.G.; Jonkman, Harry; Sawatzky, G.A. Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Telesca, R., Bolink, H., Yunoki, S., Hadziioannou, G., Duijnen, P. T. V., Snijders, J. G., ... Sawatzky, G. A. (2001). Density-functional study of the evolution of the electronic structure of oligomers of thiophene: Towards a model Hamiltonian. Physical Review B, 6315(15), [155112]. DOI: 10.1103/PhysRevB.63.155112 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. We present density-functional and time-dependent density-functional studies of the ground, ionic, and excited states of a series of oligomers of thiophene. We show that, for the physical properties, the most relevant highest occupied and lowest unoccupied molecular orbitals develop gradually from monomer molecular orbitals into occupied and unoccupied broad bands in the large length limit. We show that band gap and ionization potentials decrease with size, as found experimentally and from empirical calculations. This gives credence to a simple tight-binding model Hamiltonian approach to these systems. We demonstrate that the length dependence of the experimental excitation spectra for both singlet and triplet excitations can be very well explained with an extended Hubbard-like Hamiltonian, with a monomer on-site Coulomb and exchange interaction and a nearest-neighbor Coulomb interaction. We also study the ground and excited-state electronic structures as functions of the torsion angle between the units in a dimer, and find almost equal stabilities for the transoid and cisoid isomers, with a transition energy barrier for isomerization of only 4.3 kcal/mol. Fluctuations in the torsion angle turn out to be very low in energy, and therefore of great importance in describing even the room-temperature properties. At a torsion angle of 90°the hopping integral is switched off for the highest occupied molecular orbital levels because of symmetry, allowing a first-principles estimate of the on-site interaction minus the next-neighbor Coulomb interaction as it enters in a Hubbard-like model Hamiltonian.

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“…Es sei jedoch daran erinnert, daû die Excitonenkopplung bei Monothiopheneinheiten wegen der geringeren Oszillatorstärke eine kleinere Verschiebung der Absorptionsmaxima bewirken sollte. [14] Die möglichen Anordnungen von 1 und 2 in den Fasern wurden mit Molecular-Modeling-Methoden studiert. Eine systematische Suche mit der Clustermethode von Gavezotti [15,16] ergab eine Reihe stabiler lamellarer Strukturen innerhalb eines Energiebereichs von 10 kcal mol À1 .…”

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“…3.5 . Da bei Bithiopheneinheiten das Übergangsdipolmoment des p-p*-Übergangs mit der Molekülhauptachse zusammenfällt, [14] ist die in Abbildung 3 gezeigte Struktur ein H-Aggregat ± in exzellenter Übereinstimmung mit den experimentellen Daten. Es sei allerdings betont, daû andere lamellare Anordnungen durchaus auch mit den experimentellen Daten in Einklang sind.…”

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