An experimental determination of the heat of formation of C2 and the CH bond dissociation energy in C2H

Urdahl, Randall; Yang, Bao; Jackson, William M.

doi:10.1016/0009-2614(91)90276-f

Cited by 119 publications

(66 citation statements)

References 10 publications

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“…52 The first four experimental vibrational energy level differences (G(ν)=G ν -G 0 , ν = 1,4) for the X 1 Σ g + , a 3 Π u , b 3 Σ g -, and A 1 Π u states are shown in Figure 5 (see Table 11 in Supporting Information for numerical values). Relative to the experimental vibrational energy level differences, 47 [2] R12 results, however when the aug-ccpVDZ basis set is used the opposite trend is seen. The lower vibrational energy level differences tend to be well represented in both the ground and excited states.…”

Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

“…The errors in the zero-point energies (ZPEs) for the X 1 Σ g + , a 3 Π u , b 3 Σ g -, and A 1 Π u states computed with aug-cc-pVXZ (X = D,T,Q) relative to the experimental ZPEs 47 are presented in Table 11 Sample Timings for the Pilot Code. To provide a preliminary idea of the expense of the calculations, timing information for the pilot code has also been collected in Table 5 Since the 2-RDM from the CASSCF is used for the MRMP2 computations, the 2-RDM has already been calculated for the MRMP2 computation and there is no extra cost associated with its formation.…”

Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

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Assessment of Perturbative Explicitly Correlated Methods for Prototypes of Multiconfiguration Electronic Structure

Roskop

Kong

Valeev

et al. 2013

J. Chem. Theory Comput.

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The performance of the [2]S and [2]R12 universal perturbative corrections that account for one-and manybody basis set errors of single-and multiconfiguration electronic structure methods is assessed. A new formulation of the [2]R12 methods is used in which only strongly occupied orbitals are correlated, making the approach more amenable for larger computations. Three model problems are considered using the aug-ccpVXZ (X = D,T,Q) basis sets: the electron affinity of fluorine atom, a conformational analysis of two Si2H4structures, and a description of the potential energy surfaces of the X 1Σg+, a 3Πu, b 3Σg-, and A1Πu states of C2. In general, the [2]R12 and [2]S corrections enhance energy convergence for conventional multireference configuration interaction (MRCI) and multireference perturbation theory (MRMP2) calculations compared to their complete basis set limits. For the electron affinity of the F atom, [2]R12 electron affinities are within 0.001 eV of the experimental value. The [2]R12 conformer relative energy error for Si2H4 is less than 0.1 kcal/mol compared to the complete basis set limit. The C2 potential energy surfaces show nonparallelity errors that are within 0.7 kcal/mol compared to the complete basis set limit. The perturbative nature of the [2]R12 and [2]S methods facilitates the development of a straightforward textbased data exchange standard that connects an electronic structure code that can produce a two-particle density matrix with a code that computes the corrections. This data exchange standard was used to implement the interface between the GAMESS MRCI and MRMP2 codes and the MPQC methods is used in which only strongly occupied orbitals are correlated, making the approach more amenable for larger computations. Three model problems are considered using the aug-cc-pVXZ (X = D,T,Q) basis sets: the electron affinity of fluorine atom, a conformational analysis of two Si 2 H 4 structures, and a description of the potential energy surfaces of the X 1 Σ g + , a 3 Π u , b 3 Σ g -, and A 1 Π u states of C 2 . In general, the [2] R12 and [2] S corrections enhance energy convergence for conventional multireference configuration interaction (MRCI) and multireference perturbation theory (MRMP2) calculations compared to their complete basis set limits. For the electron affinity of the F atom, [2] R12 electron affinities are within 0.001 eV of the experimental value. The [2] R12 conformer relative energy error for Si 2 H 4 is less than 0.1 kcal/mol compared to the complete basis set limit. The C 2 potential energy surfaces show nonparallelity errors that are within 0.7 kcal/mol compared to the complete basis set limit. The perturbative nature of the [2] R12 and [2] S methods facilitates the development of a straightforward text-based data exchange standard that connects an electronic structure code that can produce a two-particle density matrix with a code that computes the corrections. This data exchange standard was used to implement the interface between the GAMESS MRCI and MRMP2 codes and t...

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Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

Assessment of Perturbative Explicitly Correlated Methods for Prototypes of Multiconfiguration Electronic Structure

Roskop

Kong

Valeev

et al. 2013

J. Chem. Theory Comput.

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“…These theoretical computations predict radiative lifetimes for the upper state of the Swan system that are within a few percent of the accurate measurements by laser-induced fluoresence reported by Naulin et al (1988). The C 2 dissociation energy is taken from an experiment involving multi-photon dissociation of acetylene: D 0 (C 2 ) = 6.297 eV (Urdahl et al 1991). Our molecular data for individual 12 C 2 lines-gf -values and excitation energies-are in excellent agreement with values listed by Asplund et al (2005) for their determination of the solar C abundance.…”

Section: The Swan Bandsmentioning

confidence: 70%

The Galactic R Coronae Borealis Stars: The C2 Swan Bands, The Carbon Problem, and The 12C/13C Ratio

Hema¹,

Pandey²,

Lambert³

2013

Proceedings of XII International Symposium on Nuclei in the Cosmos — PoS(NIC XII)

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Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C 2 Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C 2 bands are used to derive the 12 C abundance, and the (1, 0) 12 C 13 C band to determine the 12 C/ 13 C ratios. The carbon abundance derived from the C 2 Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He = 0.1%) to 10.5 (C/He = 10%). Carbon abundances derived from C i lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the "carbon problem." In principle, the carbon abundances obtained from C 2 Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C 2 bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C 2 carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the 12 C/ 13 C ratios are discussed in light of the double degenerate and the final flash scenarios.

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“…Using the data of Table 1 and assuming the C 2 + ion carrying no kinetic energy, a value of D(H-C 2 )=5.44±0.4 eV is obtained. By other experimental methods 5.20 eV and 5.11 ±0.11 eV are proposed [12,16,37]. By theoretical calculations 4.86 eV is obtained [56].…”

Section: 32mentioning

confidence: 91%

How Complex can be the Unimolecular Decomposition of a Simple Molecule? The Case of Acetylene. An Electron Impact and PIPECO Investigation

Locht

Servais

1996

Zeitschrift Für Physikalische Chemie

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The dissociative ionization of C 2 H 2 , C 2 D 2 and C 2 HD is presented in this work. Excepting the H 2 + ion formation, all dissociation channels are thoroughly investigated by electron impact. The translational energy distribution as a function of the impinging electron energy and the appearance energy as a function of the translational energy are measured for all fragment ions. KE versus AE diagrams are obtained and the isotope effect is examined. All observed thresholds are analyzed in detail and dissociation mechanisms are proposed. For the C 2 H + ion, the PIPECO technique has also been used. From these discussions the H-C 2 H, HC≡CH and H-C 2 binding energy values are proposed, i.e. 5.33±0.23eV, 9.83±0.10eV and 5.44±0.40 eV respectively. The fragmentation paths leading to C + , CH 2 + and C 2 + are discussed in terms of dissociation mechanisms involving the transient vinylidene structure of the molecular ion as an intermediate.

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An experimental determination of the heat of formation of C2 and the CH bond dissociation energy in C2H

Cited by 119 publications

References 10 publications

Assessment of Perturbative Explicitly Correlated Methods for Prototypes of Multiconfiguration Electronic Structure

Assessment of Perturbative Explicitly Correlated Methods for Prototypes of Multiconfiguration Electronic Structure

The Galactic R Coronae Borealis Stars: The C2 Swan Bands, The Carbon Problem, and The 12C/13C Ratio

How Complex can be the Unimolecular Decomposition of a Simple Molecule? The Case of Acetylene. An Electron Impact and PIPECO Investigation

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