Photoelectron spectra and electronic structures of highly substituted polyenes

Rademacher, Paul; Kowski, Klaus; Hopf, Henning; Klein, Dagmar; Klein, Oliver; Suhrada, Christopher P.

doi:10.1016/s0022-2860(01)00530-0

Cited by 10 publications

(8 citation statements)

References 16 publications

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“…We thus move now to a comparison with experimental results, and in Table I we summarize the results for shorter oligomers, for which experimental data are available [7,[75][76][77]. We first list the values coming directly from the negative of the HOMO eigenvalue (columns on the left) using the aforementioned different mean-field methods (KS and HF).…”

Section: B Ip Of the Transacetylene Oligomer Seriesmentioning

confidence: 99%

“…There has thus been a search for theoretical methods that can give us accuracy together with feasibility of calculations, spanning a wide range of both inorganic and organic molecular systems [3][4][5][6]. In particular, the class of linear or quasilinear molecular systems-oligomers or polymers-offers a special work space that allows one to concentrate on the length dependence (just one relevant dimension) of the properties of interest: indeed, the dependence and evolution of the IP, the EA, and the electronic gaps with structural characteristics or compositions is a topic of intense study [7][8][9][10][11][12]. For short oligomers in fixed geometries, as for small molecules, these properties can be obtained with high accuracy from high-level quantum-chemistry calculations that go beyond the mean-field approximation, serving as benchmarks for other computational electronic structure approaches [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Length dependence of ionization potentials of transacetylenes: Internally consistent DFT/GWapproach

et al. 2015

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We follow the evolution of the ionization potential (IP) for the paradigmatic quasi-one-dimensional transacetylene family of conjugated molecules, from short to long oligomers and to the infinite polymer transpolyacetylene (TPA). Our results for short oligomers are very close to experimental available data. We find that the IP varies with oligomer length and converges to the given value for TPA with a smooth, coupled inverse-length-exponential behavior. Our prediction is based on an "internally consistent" scheme to adjust the exchange mixing parameter α of the PBEh hybrid density functional, so as to obtain a description of the electronic structure consistent with the quasiparticle approximation for the IP. This is achieved by demanding that the corresponding quasiparticle correction, in the GW @PBEh approximation, vanishes for the IP when evaluated at PBEh(α ic ). We find that α ic is also system-dependent and converges with increasing oligomer length, enabling the dependence of the IP and other electronic properties to be identified.

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Section: B Ip Of the Transacetylene Oligomer Seriesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Length dependence of ionization potentials of transacetylenes: Internally consistent DFT/GWapproach

et al. 2015

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“…It can be seen that, by decreasing length of the polyene chain, the position of the first feature moves to the higher binding energy. In addition, Rademacher et al 73 recorded the valence photoelectron spectra of some substituted polyene chains with different lengths. They showed that, with the decrease the length of chain, the first feature in the photoelectron spectrum moves to the higher binding energy.…”

Section: And Compared With the Corresponding Theoretical Values Taken...mentioning

confidence: 99%

Photoelectron Spectra of Some Important Biological Molecules: Symmetry-Adapted-Cluster Configuration Interaction Study

Farrokhpour

Ghandehari

2013

J. Phys. Chem. B

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In this work, the valence vertical ionization energies (up to 5) of some important biologically active molecules including 2,4-dinitrophenol, 2,4-dinitroanisole, nicotinic acid, nicotinic acid methyl ester, nicotinamide, N,N-diethylnicotinamide, barbituric acid, uric acid, cytosine, β-carotene, and menadione were calculated in the gas phase and compared with the experimental data reported in the literature. The symmetry-adapted-cluster configuration interaction (SAC-CI) general-R method was used to calculate the ionization energies. The intensity of each ionization band was evaluated using the monopole approximation. Comparison of the calculated photoelectron spectrum of each molecule with its corresponding experimental spectra allowed for assigning the photoelectron bands by natural bonding orbital (NBO) calculations even though some of the associated bands were significantly overlapped for some molecules. Among the considered molecules, there was no agreement between the experimental and calculated photoelectron spectrum of β-carotene. The reason for this disagreement was theoretically investigated and attributed to the degradation and decomposition of β-carotene. The calculated first ionization energies of the considered molecules were correlated with their Hückel k-index to obtain Coulomb (α) and resonance (β) integrals of the Hückel molecular orbital theory for the biomolecules considered in this study. A linear correlation was found between the first ionization energy and the Hückel k-index.

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“…Inicialmente, ainda tratando de acetilenos, selecionamos um derivado alquílico do oligômero com n=7 (ver Fig. 4.2) para o qual o espectro de fotoemissão foi medido em fase gasosa [71], e realizamos cálculos DFT e GW para avaliar a performance do funcional OPBEh. Neste caso, todas as coordenadas atômicas do oligômero foram previamente otimizadas no nível de teoria PBE+vdW/tier2 para obtermos a geometria do estado fundamental.…”

Section: Sistemas Conjugados 1dunclassified

“…Em suma, a consistência entre os métodos GW e OPBEh resulta numa boa estimativa para as duas primeiras energias de ionização experimentais e, além disso, também preserva as principais características do espectro experimental. Figura 4.3: Espectro de níveis de energia DFT e QP do oligômero tb-OTA7 convoluídos com gaussianas de 0,25 eV, comparado com o espectro de fotoemissão experimental de fase gasosa [71].…”

Section: Sistemas Conjugados 1dunclassified

Propriedades eletrônicas de sistemas conjugados: importância da troca exata

Pinheiro¹,

Fernandes²

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Photoelectron spectra and electronic structures of highly substituted polyenes

Cited by 10 publications

References 16 publications

Length dependence of ionization potentials of transacetylenes: Internally consistent DFT/GWapproach

Length dependence of ionization potentials of transacetylenes: Internally consistent DFT/GWapproach

Photoelectron Spectra of Some Important Biological Molecules: Symmetry-Adapted-Cluster Configuration Interaction Study

Propriedades eletrônicas de sistemas conjugados: importância da troca exata

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