Electronic spectra of hexacene in solution (ground state. Triplet state. Dication and dianion)

Angliker, Herbert; Rommel, Erika; Wirz, Jakob

doi:10.1016/0009-2614(82)83589-6

Cited by 125 publications

(153 citation statements)

References 26 publications

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“…This is a very unexpected result. We note that a similar trend can be found with the acenes [21]. As a first approximation, for the conjugated polymers a least squares fit to the data yields…”

supporting

confidence: 77%

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Triplet Energies ofπ-Conjugated Polymers

et al. 2001

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confidence: 77%

“…1.3 6 0.25 eV. For comparison, with polyacenes it is suggested that the first member with a triplet ground state will be nonacene [21]. From literature data, we estimate an energy for its lowest singlet state to be ca.…”

mentioning

confidence: 94%

Triplet Energies ofπ-Conjugated Polymers

et al. 2001

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“…8,9 Naphthacene ͑also referred to as tetracene͒, pentacene, and derivative compounds have been used recently to prepare highly ordered conducting organic materials or thin films with particularly large charge carrier mobilities. 10 In contrast with the prevailing view 11 that large acenes have a closed-shell singlet or open-shell triplet electronic ground states, a few groups [12][13][14][15][16] recently conjectured that large acenes such as hexacene, heptacene, or octacene should rather be regarded as open-shell singlet biradical systems, as a result of the instability of unrestricted ͑UBLYP, UB3LYP, UPW91, UBPW91, etc.͒ wave functions, in conjunction with rather modest basis sets ͑STO-3G, 6-31G ‫ء‬ , or cc-pVDZ͒. This in-stability was diagnosed 12 from the fact that in these unrestricted calculations the two outermost singly occupied ␣ and ␤ spin orbitals do not smoothly follow the D 2h symmetry point group imposed by the nuclear frame, but rather reflect an overwhelmingly strong symmetry breaking of the electronic wave function, 12 in the form of a localization of the two frontier electrons on opposite polyacetylenic strands.…”

Section: Introductionmentioning

confidence: 79%

A benchmark theoretical study of the electronic ground state and of the singlet-triplet split of benzene and linear acenes

Hajgató

Szieberth

Geerlings

et al. 2009

The Journal of Chemical Physics

200

216

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A benchmark theoretical study of the electronic ground state and of the vertical and adiabatic singlet-triplet ͑ST͒ excitation energies of benzene ͑n =1͒ and n-acenes ͑C 4n+2 H 2n+4 ͒ ranging from naphthalene ͑n =2͒ to heptacene ͑n =7͒ is presented, on the ground of single-and multireference calculations based on restricted or unrestricted zero-order wave functions. High-level and large scale treatments of electronic correlation in the ground state are found to be necessary for compensating giant but unphysical symmetry-breaking effects in unrestricted single-reference treatments. The composition of multiconfigurational wave functions, the topologies of natural orbitals in symmetry-unrestricted CASSCF calculations, the T1 diagnostics of coupled cluster theory, and further energy-based criteria demonstrate that all investigated systems exhibit a 1 A g singlet closed-shell electronic ground state. Singlet-triplet ͑S 0 -T 1 ͒ energy gaps can therefore be very accurately determined by applying the principles of a focal point analysis onto the results of a series of single-point and symmetry-restricted calculations employing correlation consistent cc-pVXZ basis sets ͑X=D, T, Q, 5͒ and single-reference methods ͓HF, MP2, MP3, MP4SDQ, CCSD, CCSD͑T͔͒ of improving quality. According to our best estimates, which amount to a dual extrapolation of energy differences to the level of coupled cluster theory including single, double, and perturbative estimates of connected triple excitations ͓CCSD͑T͔͒ in the limit of an asymptotically complete basis set ͑cc-pVϱZ͒, the S 0 -T 1 vertical excitation energies of benzene ͑n =1͒ and n-acenes ͑n =2-7͒ amount to 100.79, 76.28, 56.97, 40.69, 31.51, 22.96, and 18.16 kcal/mol, respectively. Values of 87.02, 62.87, 46.22, 32.23, 24.19, 16.79, and 12.56 kcal/mol are correspondingly obtained at the CCSD͑T͒ / cc-pVϱZ level for the S 0 -T 1 adiabatic excitation energies, upon including B3LYP/cc-PVTZ corrections for zero-point vibrational energies. In line with the absence of Peierls distortions, extrapolations of results indicate a vanishingly small S 0 -T 1 energy gap of 0 to ϳ4 kcal/ mol ͑ϳ0.17 eV͒ in the limit of an infinitely large polyacene.

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“…1,2 Due to their technological potential [3][4][5] and their intrinsic value as models for more complex conjugated molecules, they have been the subject of many theoretical and experimental investigations. [6][7][8][9][10][11][12][13][14] In a number of recent studies, it has been proposed that longer acenes may possess an unusual electronic ground state that is not the simple closed-shell singlet suggested by molecular orbital arguments. Based on extrapolating the experimental singlet-triplet gap of the acenes up to pentacene, Angliker et al 7 predicted that the ground state of higher acenes from nonacene upwards would be a triplet.…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8][9][10][11][12][13][14] In a number of recent studies, it has been proposed that longer acenes may possess an unusual electronic ground state that is not the simple closed-shell singlet suggested by molecular orbital arguments. Based on extrapolating the experimental singlet-triplet gap of the acenes up to pentacene, Angliker et al 7 predicted that the ground state of higher acenes from nonacene upwards would be a triplet. Density functional calculations by Houk et al 11 also predicted a singlet-triplet cross over.…”

Section: Introductionmentioning

confidence: 99%

The radical character of the acenes: A density matrix renormalization group study

Hachmann

Dorando

Aviles

et al. 2007

The Journal of Chemical Physics

469

619

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We present a detailed investigation of the acene series using high-level wave function theory. Our ab initio density matrix renormalization group algorithm has enabled us to carry out complete active space calculations on the acenes from napthalene to dodecacene correlating the full -valence space. While we find that the ground state is a singlet for all chain lengths, examination of several measures of radical character, including the natural orbitals, effective number of unpaired electrons, and various correlation functions, suggests that the longer acene ground states are polyradical in nature.

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Electronic spectra of hexacene in solution (ground state. Triplet state. Dication and dianion)

Cited by 125 publications

References 26 publications

Triplet Energies ofπ-Conjugated Polymers

Triplet Energies ofπ-Conjugated Polymers

A benchmark theoretical study of the electronic ground state and of the singlet-triplet split of benzene and linear acenes

The radical character of the acenes: A density matrix renormalization group study

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