Theoretical investigation of the electronic spectrum of pyrazine

Woywod, Clemens; Papp, Anita; Halász, Gábor J.; Vibók, Ágnes

doi:10.1007/s00214-009-0678-x

Cited by 20 publications

(24 citation statements)

References 32 publications

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“…For states of both spin symmetries, the CC3 and CCSDT transitions energies are slightly larger than the available electron impact/multi-photon measurements, [219][220][221][222][223] but do provide energetic gaps between ES very similar to the measured ones. There are many available studies of the ES of pyrazine, 23,24,26,27,30,65,68,118,158,181,210,211,216,224,225 and tetrazine, [23][24][25][26][27]65,68,118,158,210,211,[226][227][228][229][230][231] for which the 2ℎ symmetry helps distinguishing the different ES. Our results are collected in Tables 8 and S8.…”

Section: Benzene Pyrazine and Tetrazinementioning

confidence: 99%

A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules

Loos

Lipparini²,

Boggio‐Pasqua³

et al. 2019

Preprint

110

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<div><div><div><p>Following our previous work focussing on compounds containing up to 3 non-hydrogen atoms [J. Chem. Theory Comput. 14 (2018) 4360–4379], we present here highly-accurate vertical transition energies obtained for 27 molecules encompassing 4, 5, and 6 non-hydrogen atoms: acetone, acrolein, benzene, butadiene, cyanoacetylene, cyanoformaldehyde, cyanogen, cyclopentadiene, cyclopropenone, cyclopropenethione, diacetylene, furan, glyoxal, imidazole, isobutene, methylenecyclopropene, propynal, pyrazine, pyridazine, pyridine, pyrimidine, pyrrole, tetrazine, thioacetone, thiophene, thiopropynal, and triazine. To obtain these energies, we use equation-of-motion coupled cluster theory up to the highest technically possible excitation order for these systems (CC3, EOM-CCSDT, and EOM-CCSDTQ), selected configuration interaction (SCI) calculations (with tens of millions of determinants in the reference space), as well as the multiconfigurational 𝑛-electron valence state perturbation theory (NEVPT2) method. All these approaches are applied in combination with diffuse-containing atomic basis sets. For all transitions, we report at least CC3/aug-cc-pVQZ vertical excitation energies as well as CC3/aug-cc-pVTZ oscillator strengths for each dipole-allowed transition. We show that CC3 almost systematically delivers transition energies in agreement with higher-level methods with a typical deviation of ±0.04 eV, except for transitions with a dominant double excitation character where the error is much larger. The present contribution gathers a large, diverse and accurate set of more than 200 highly-accurate transition energies for states of various natures (valence, Rydberg, singlet, triplet, 𝑛 → 𝜋★, 𝜋 → 𝜋★, . . . ). We use this series of theoretical best estimates to benchmark a series of popular methods for excited state calculations: CIS(D), ADC(2), CC2, STEOM-CCSD, EOM-CCSD, CCSDR(3), CCSDT-3, CC3, as well as NEVPT2. The results of these benchmarks are compared to the available literature data.</p></div></div></div>

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Section: Benzene Pyrazine and Tetrazinementioning

confidence: 99%

A Mountaineering Strategy to Excited States: Highly-Accurate Energies and Benchmarks for Medium Size Molecules

Loos

Lipparini²,

Boggio‐Pasqua³

et al. 2019

Preprint

110

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“…[32][33][34][35][36] The latter provide a basis for the description of the electronic excited states in our scattering calculations. These studies have reported that most of these states are valence in character with the exception of perhaps just four higher-lying (found in calculations above 7 eV) Rydberg singlet states 32 and a diffuse 3 B 2u (Ref. 34) state with an experimentally determined vertical excitation energy of about 4.50 eV.…”

Section: The Calculations Of Winstead and Mckoy Found Evidence Formentioning

confidence: 99%

Elastic and inelastic low-energy electron collisions with pyrazine

Mašín

Gorfinkiel

2011

The Journal of Chemical Physics

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We present results of ab-initio scattering calculations for electron collisions with pyrazine using the R-matrix method, carried out at various levels of approximation. We confirm the existing experimental and theoretical understanding of the three well-known π * shape resonances. In addition, we find numerous core-excited resonances (above 4.8 eV) and identify their most likely parent states. We also present differential cross sections, showing high sensitivity to the scattering model chosen at low energies. We make recommendations regarding the selection of models for scattering calculations with this type of targets.

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“…In addition, we included four s-, three p-, and three d-type diffuse functions located at the center of mass of the molecule, whose exponents are s The ground state geometry and force field have been determined by the single-state CASPT2 approach. 57 47 We therefore use 1 1 B 3u and 1 1 B 2u to label these states in this article.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…The oscillator strengths were computed by combining transition dipole moments and vertical excitation energies obtained at the CASSCF and CASPT2 levels of theory, respectively. 47 …”

Section: Xms-caspt2 Theorymentioning

confidence: 99%