Singlet La and Lb Bands for N-Acenes (N = 2–7): A CASSCF/CASPT2 Study

Bettanin, Fernanda; Ferrão, Luiz F. A.; Pinheiro, Max; Aquino, Adélia J. A.; Lischka, Hans; Machado, Francisco B. C.; Nachtigallová, Dana

doi:10.1021/acs.jctc.7b00302

Cited by 31 publications

(41 citation statements)

References 72 publications

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“…The concept of a structure related topological phase transition and the corresponding bandgap closure is exemplified in Fig 1A for the structure family of ethynylene-bridged polyacene polymers. Both DFT and tight-binding calculations shows a monotonic decrease of the HOMO-LUMO gap of the polyacene monomer as a function of the acene size (where n denotes the number of benzene rings of the polyacene) (24) (see also Fig. S1), as expected from the increasing delocalization of the frontier orbitals.…”

Section: Main Textmentioning

confidence: 68%

Tailoring topological order and π-conjugation to engineer quasi-metallic polymers

Cirera¹,

Sánchez‐Grande²,

Torre³

et al. 2020

Nat. Nanotechnol.

128

141

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D.E.) † Equally contributing authors. One Sentence Summary:The on-surface chemical reactions of molecular precursors on a pristine Au(111) surfaces results in the formation of long, defect-free, -conjugated polymers featuring a topological non-trivial SSH quantum phase, with a very narrow bandgap due to the proximity to the point of topological transition, in-gap zero-energy edge-states and electronic transformation of the π-conjugated polymers.

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Section: Main Textmentioning

confidence: 68%

Tailoring topological order and π-conjugation to engineer quasi-metallic polymers

Cirera¹,

Sánchez‐Grande²,

Torre³

et al. 2020

Nat. Nanotechnol.

128

141

View full text Add to dashboard Cite

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“…949 A recent CASPT2 study investigated the different computational requirements for describing the La and Lb states of polyacenes. 952 As opposed to the MR studies, which showed rather uniform trends for the excitation energies, a DFT study presented some evidence suggesting that the optical gaps oscillate with increasing size of the oligoacene. 953 Finally, a recent CASPT2 study 540 In addition to polyacenes, a wide range of other PAHs have been studied by multireference methods.…”

Section: Polycyclic Aromatic Systems: Monomers and Dimersmentioning

confidence: 88%

Multireference Approaches for Excited States of Molecules

et al. 2018

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Understanding the properties of electronically excited states is a challenging task that becomes increasingly important for numerous applications in chemistry, molecular physics, molecular biology, and materials science. A substantial impact is exerted by the fascinating progress in time-resolved spectroscopy, which leads to a strongly growing demand for theoretical methods to describe the characteristic features of excited states accurately. Whereas for electronic ground state problems of stable molecules the quantum chemical methodology is now so well developed that informed nonexperts can use it efficiently, the situation is entirely different concerning the investigation of excited states. This review is devoted to a specific class of approaches, usually denoted as multireference (MR) methods, the generality of which is needed for solving many spectroscopic or photodynamical problems. However, the understanding and proper application of these MR methods is often found to be difficult due to their complexity and their computational cost. The purpose of this review is to provide an overview of the most important facts about the different theoretical approaches available and to present by means of a collection of characteristic examples useful information, which can guide the reader in performing their own applications.

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“…The latter geometries were very similar to def2-SVP optimized ones ( Regarding the monomer (TABLE V), DFT/MRCI predicts excitation energies of 2.69 and 3.27 eV for 1 1 B2u and 1 1 B3u states, in excellent agreement with experimental results 87,88 and previously reported calculations with DFT/MRCI, 85 using both SV(P) and TZVP basis sets, and CASPT2. 86 Other methods predict higher excitation energies for both states and a varying energy gap between them, such as 0. There is an overall good agreement among dimer spectra using different methods (FIG.…”

Section: B Dimer Vertical Excitations At Optimized Geometriesmentioning

confidence: 99%

Excitonic and charge transfer interactions in tetracene stacked and T-shaped dimers

Valente

Casal

Barbatti

et al. 2021

The Journal of Chemical Physics

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Extended quantum chemical calculations were performed for the tetracene dimer to provide benchmark results, analyze the excimer survival process, and explore the possibility of using long-range-corrected (LC) time-dependent (TD) second-order density functional tight-biding (DFTB2) for this system.Ground-and first-excited-states optimized geometries, vertical excitations at relevant minima, and intermonomer displacement potential energy curves (PECs) were calculated for these purposes. Groundstate geometries were optimized with the scaled-opposite-spin (SOS) second-order Møller-Plesset perturbation theory (MP2) and LC-DFT (density functional theory) and LC-DFTB2 levels. Excited-state geometries were optimized with SOS-ADC(2) (algebraic diagrammatic construction to second-order) and the time-dependent approaches for the latter two methods. Vertical excitations and PECs were 1 This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in D. C. A. Valente et al. J. Chem. Phys.

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Singlet L_a and L_b Bands for N-Acenes (N = 2–7): A CASSCF/CASPT2 Study

Cited by 31 publications

References 72 publications

Tailoring topological order and π-conjugation to engineer quasi-metallic polymers

Tailoring topological order and π-conjugation to engineer quasi-metallic polymers

Multireference Approaches for Excited States of Molecules

Excitonic and charge transfer interactions in tetracene stacked and T-shaped dimers

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