Electron Propagator Theory of Guanine and Its Cations:  Tautomerism and Photoelectron Spectra

Dolgounitcheva, O.; Zakrzewski, and V. G.; Ortiz, J. V.

doi:10.1021/ja0015747

Cited by 80 publications

(91 citation statements)

References 28 publications

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“…However, the ADC͑3͒ calculations suggested strong orbital electron correlation in those cases where the spectroscopic pole strengths were less than 0.80. 38 For example, the next-HOMO ͑NHOMO͒, 1a u , and the last outer valence orbital, 5b u , show strong electron correlation with the corresponding dominant pole strengths being 0.63 and 0.54, respectively, 5 as seen in Table III. This caused their OVGF method to fail to reproduce the ionization energies for these states.…”

Section: Ionization Energies Of the Conformers In Outer Valence Spacementioning

confidence: 96%

“…Dyson orbitals represent the changes in electronic structure accompanying the detachment of an electron from a molecule. 38 Corresponding to each ionization energy in the DFT calculations, the Dyson orbitals are proportional to canonical, Kohn-Sham ͑KS͒ orbitals. 39 The simulation procedure for orbital momentum distributions of the 1,3-butadiene conformers was based on the experimental conditions of a previous EMS study.…”

Section: -24mentioning

confidence: 99%

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Coexistence of 1,3-butadiene conformers in ionization energies and Dyson orbitals

Saha

Wang

Falzon

et al. 2005

The Journal of Chemical Physics

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The minimum-energy structures on the torsional potential-energy surface of 1,3-butadiene have been studied quantum mechanically using a range of models including ab initio Hartree-Fock and second-order Møller-Plesset theories, outer valence Green's function, and density-functional theory with a hybrid functional and statistical average orbital potential model in order to understand the binding-energy ͑ionization energy͒ spectra and orbital cross sections observed by experiments. The unique full geometry optimization process locates the s-trans-1,3-butadiene as the global minimum structure and the s-gauche-1,3-butadiene as the local minimum structure. The latter possesses the dihedral angle of the central carbon bond of 32.81°in agreement with the range of 30°-41°obtained by other theoretical models. Ionization energies in the outer valence space of the conformer pair have been obtained using Hartree-Fock, outer valence Green's function, and density-functional ͑statistical average orbital potentials͒ models, respectively. The Hartree-Fock results indicate that electron correlation ͑and orbital relaxation͒ effects become more significant towards the inner shell. The spectroscopic pole strengths calculated in the Green's function model are in the range of 0.85-0.91, suggesting that the independent particle picture is a good approximation in the present study. The binding energies from the density-functional ͑statisticaly averaged orbital potential͒ model are in good agreement with photoelectron spectroscopy, and the simulated Dyson orbitals in momentum space approximated by the density-functional orbitals using plane-wave impulse approximation agree well with those from experimental electron momentum spectroscopy. The coexistence of the conformer pair under the experimental conditions is supported by the approximated experimental binding-energy spectra due to the split conformer orbital energies, as well as the orbital momentum distributions of the mixed conformer pair observed in the orbital cross sections of electron momentum spectroscopy.

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Section: Ionization Energies Of the Conformers In Outer Valence Spacementioning

confidence: 96%

Section: -24mentioning

confidence: 99%

Coexistence of 1,3-butadiene conformers in ionization energies and Dyson orbitals

Saha

Wang

Falzon

et al. 2005

The Journal of Chemical Physics

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“…Theoretical work by Dolgounitcheva et al 23 confirms that this is at least the case for tautomers 1-5. Therefore, the shapes of the PIE curves up to 9 eV depend mostly on the Franck-Condon overlap of the neutral and cation ground electronic states, which differ for the different tautomers.…”

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confidence: 86%

Experimental Observation of Guanine Tautomers with VUV Photoionization

et al. 2009

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Two methods of preparing guanine in the gas phase, thermal vaporization and laser desorption, have been investigated. The guanine generated by each method is entrained in a molecular beam, single-photon ionized with tunable VUV synchrotron radiation, and analyzed using reflectron mass spectrometry. The recorded photoionization efficiency (PIE) curves show a dramatic difference for experiments performed via thermal vaporization compared to that with laser desorption. The calculated vertical and adiabatic ionization energies for the eight lowest-lying tautomers of guanine suggest that the experimental observations arise from different tautomers being populated in the two different experimental methods.

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“…Similar effects concerning nearly degenerate energy levels, due to the ionization of nonbonding n-type lone-pairs (LPs) and -orbitals, has been observed in other heteroaromatic molecules, such as adenine, 49-51 pyrimidine 52 and purine, 52 where the LPs belong to the nitrogen atoms. In thymine, 50,51,53 uracil, and the uracil derivatives, [54][55][56] the LPs involved belong to the oxygen atoms outside the aromatic ring; and in guanine 51,57,58 the LPs have a mixed nitrogen-oxygen character.…”

Section: Introductionmentioning

confidence: 99%

“…The shifts in the HF ionization energies are non-uniform, and are much larger for the n-levels than for the -levels. This effect is more pronounced in the propagator results 35,47,48,50,[53][54][55][56][57][58][59] than in those employing the EOM-IP-CC approach. 51 Previously, the ionization of pyridine has been studied theoretically by Suzuki and Suzuki, 41 using the continuum multiple scattering X (CMS-X) method, by Wan et al, 42 and Kitao and Nakatsuji, 43 using the SAC-CI method, and by Plashkevych et al 44 using…”

Section: Introductionmentioning

confidence: 99%

Ionization of pyridine: Interplay of orbital relaxation and electron correlation

Trofimov

Holland

Powis

et al. 2017

The Journal of Chemical Physics

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The valence shell ionization spectrum of pyridine was studied using the third-order algebraicdiagrammatic construction [ADC(3)] approximation scheme for the one-particle Green's function and the outer-valence Green's function (OVGF) method. The results were used to interpret angle resolved photoelectron spectra recorded with synchrotron radiation in the photon energy range of 17 -120 eV. The lowest four states of the pyridine radical cation, and CCSD (coupled-cluster singles and doubles) methods, and the harmonic vibrational frequencies were obtained at the MP2 level of theory for the lowest three cation states. The results were used to estimate the adiabatic 0-0 ionization energies, which were then compared to the available experimental and theoretical data. Photoelectron anisotropy parameters and photoionization partial cross-sections, derived from the experimental spectra, were compared to predictions obtained with the continuum multiple scattering approach.3

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Electron Propagator Theory of Guanine and Its Cations: Tautomerism and Photoelectron Spectra

Cited by 80 publications

References 28 publications

Coexistence of 1,3-butadiene conformers in ionization energies and Dyson orbitals

Coexistence of 1,3-butadiene conformers in ionization energies and Dyson orbitals

Experimental Observation of Guanine Tautomers with VUV Photoionization

Ionization of pyridine: Interplay of orbital relaxation and electron correlation

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