Adiabatic Electron Affinities of Oligophenyls: Anion Photoelectron Spectroscopy and Density Functional Theory Study

Nakamura, Tsuneyuki; Ando, Naoto; Matsumoto, Yukino; Furuse, Shunsuke; Mitsui, Masaaki; Nakajima, Atsushi

doi:10.1246/cl.2006.888

Cited by 9 publications

(22 citation statements)

References 14 publications

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“…Beyond this sharp increase the gap varies smoothly, almost remaining constant, with the ribbon length. As shown in the upper panel of the Figure, the calculated gap for n=1 is in excellent agreement with the available experimental data [37][38][39][40][41] . Finally, in the lower panel of the Figure, the results for the S-CDW solution in the ribbon with n=7 are also depicted.…”

Section: Resultssupporting

confidence: 87%

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Graphene Nano-Ribbons: Major differences in the fundamental gap as its length is increased either in the zig-zag or the armchair directions

Vergés¹,

Chiappe²,

Louis³

2016

Preprint

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Controlling the forbidden gap of graphene nano-ribbons (GNR) is a major challenge that has to be attained if this attractive material has to be used in micro-and nano-electronics. Using an unambiguous notation {m,n}-GNR, where m(n) is the number of six carbon rings in the arm-chair (zig-zag) directions, we investigate how varies the HOMO-LUMO gap when the size of the GNR is varied by increasing either m or n, while keeping the other variable fixed. It is shown that no matter whether charge-or spin-density-waves solutions are considered, the gap varies smoothly when n is kept fixed whereas it oscillates when the opposite is done, posing serious difficulties to the control of the gap. It is argued that the origin of this behavior is the fact that excess or defect charges or magnetic moments are mostly localised at zig-zag edges.

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Section: Resultssupporting

confidence: 87%

“…All ribbons here investigated had the edge dangling σ bonds passivated by hydrogen atoms. [37,38,39,40,41] are included in the upper plot (see also [5]).…”

Section: Methodsmentioning

confidence: 99%

Graphene Nano-Ribbons: Major differences in the fundamental gap as its length is increased either in the zig-zag or the armchair directions

Vergés¹,

Chiappe²,

Louis³

2016

Preprint

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“…where the degree of spin contamination is vanishingly small for the semilocal functionals and global hybrid functionals, but is noticeable for the LC hybrid functionals [100]. The results are consistent with the argument that the larger fraction of HF exchange adopted of short-chain n-PP (n ≤ 4) calculated using ωB97 and ωB97X match very well with the experimental data: Expt1 (vertical EA) [110,111] and Expt2 (adiabatic EA) [112,113],…”

Section: Resultssupporting

confidence: 79%

“…(vertical IP − vertical EA) [76,110,111] and Expt2 (vertical IP − adiabatic EA) [76,112,113], are taken from the literature.…”

Section: Discussionmentioning

confidence: 99%

Electronic and Optical Properties of the Narrowest Armchair Graphene Nanoribbons Studied by Density Functional Methods

Yeh¹,

Lee²,

Chai³

2016

Aust. J. Chem.

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In the present study, a series of planar poly(p-phenylene) (PPP) oligomers with n phenyl rings (n = 1−20), designated as n-PP, are taken as finite-size models of the narrowest armchair graphene nanoribbons with hydrogen passivation. The singlet-triplet energy gap, vertical ionization potential, vertical electron affinity, fundamental gap, optical gap, and exciton binding energy of n-PP are calculated using Kohn-Sham density functional theory and time-dependent density functional theory with various exchange-correlation density functionals. The ground state of n-PP is shown to be singlet for all the chain lengths studied. In contrast to the lowest singlet state (i.e., the ground state), the lowest triplet state and the ground states of the cation and anion of n-PP are found to exhibit some multi-reference character. Overall, the electronic and optical properties of n-PP obtained from the ωB97 and ωB97X functionals are in excellent agreement with the available experimental data. † These authors contributed equally to this work.

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“…Thus DFT with moderate basis sets was proven to be adequate to calculate properties of n-doped conjugated oligomers. 57 The same reasoning applies to excited-state calculations, which are much more complicated for small than for large systems. 58 Nonetheless, excited-state calculations of anions might require diffuse functions.…”

Section: Methodsmentioning

confidence: 93%

Theoretical Investigation of Excited States of Oligothiophene Anions

Alkan

Salzner

2008

J. Phys. Chem. A

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Electron-hole symmetry upon p-and n-doping of conducting organic polymers is rationalized with Hückel theory by the presence of symmetrically located intragap states. Since density functional theory (DFT) predicts very different geometries and energy level diagrams for conjugated π-systems than semiempirical methods, it is an interesting question whether DFT confirms the existence of electron-hole symmetry predicted at the Hückel level. To answer this question, geometries of oligothiophene anions with 5-19 rings were optimized and their UV/vis spectra were calculated with time-dependent DFT. Although DFT does not produce symmetrically placed sub-band energy levels, spectra of cations and anions are almost identical. The similarity in transition energies and oscillator strengths of anions and cations can be explained by the fact that the single sub-band energy level of cations lies above the valence band by the same amount of energy as the single sub-band level of anions lies below the conduction band. This and the resemblance of the energy level spacings in valence bands of cations to those in conduction bands of anions give rise to peaks with equal energies and oscillator strengths.

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Adiabatic Electron Affinities of Oligophenyls: Anion Photoelectron Spectroscopy and Density Functional Theory Study

Cited by 9 publications

References 14 publications

Graphene Nano-Ribbons: Major differences in the fundamental gap as its length is increased either in the zig-zag or the armchair directions

Graphene Nano-Ribbons: Major differences in the fundamental gap as its length is increased either in the zig-zag or the armchair directions

Electronic and Optical Properties of the Narrowest Armchair Graphene Nanoribbons Studied by Density Functional Methods

Theoretical Investigation of Excited States of Oligothiophene Anions

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