Theoretical studies of the RSOO, ROSO, RSO2 and HOOS (R=H, CH3) radicals

Laakso, Dianna; Smith, Casey; Goumri, Abdellatif; Rocha, John-David R.; Marshall, Paul

doi:10.1016/0009-2614(94)00845-0

Cited by 38 publications

(94 citation statements)

References 32 publications

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“…Use of MP2 rather than HF frequencies to obtain the ZPE is a modification of the original G2 method; we have summarized the slightly altered energies of relevant one-, two-and threeatom species elsewhere. 19 …”

Section: Ab Initio Methodologymentioning

confidence: 99%

“…17 Morris and Jackson 18 characterized HSO 2 and HOSO at the MP4/DZP//MP2/DZP level, while we have published an investigation of these two molecules plus HSOO and HOOS carried out with Gaussian-2 (G2) theory, and focused on their thermochemistry. 19 The G2 methodology has a target accuracy of (8 kJ mol -1 for atomization enthalpies and an average absolute deviation of 5 kJ mol -1 for a set of 55 test molecules [20][21][22] and yields approximate QCISD(T)/6-311+G-(3df,2p) energies. These results for bound minima were combined with empirically estimated barrier heights in a recent flame mechanism by Glarborg et al 23 Very recently, Qi et al published MP2/6-311G(d,p) values for the geometries, frequencies, and energies in the H + SO 2 system 24 and Tureček et al 11 used G2(MP2) theory to investigate neutral and ionic HSO 2 species and transition states.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO₂ and HS + O₂

et al. 1999

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Unimolecular pathways for the isomerization and/or dissociation of HSOO, HOSO, HSO 2 , and HOOS to H + SO 2 and OH + SO have been investigated computationally, as well as HSO formation via an HSOO intermediate. The atmospheric lifetime of HSO 2 is discussed. Some pathways have no barrier, including OH + SO f HOSO and H + SOO f HSOO and SOOH, while structures and vibrational frequencies of transition states for HOSO f H + SO 2 , HOOS f OH + SO, HOSO f HSO 2 , HSOO f HS + O 2 , and HSO 2 f H + SO 2 have been characterized at the MP2)FULL/6-31G(d) level. Some geometries were further refined at the QCISD/6-311G(d,p) level. Gaussian-2 theory was employed to calculate approximate QCISD(T)/6-311+G-(3df,2p) energy barriers, and the kinetics were analyzed by RRKM theory. Rate constant expressions at the high and low-pressure limits and thermochemical properties for transient intermediates are tabulated, and the results are discussed in the context of atmospheric and combustion chemistry. A revised theoretical H-OSO bond strength is compatible with the flame data for SO 2 -catalyzed recombination of H atoms.

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Section: Ab Initio Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO₂ and HS + O₂

et al. 1999

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“…Similar methodologies such as G2 and G2(MP2) have produced different values, but the reactions used were not the same. The reaction employed by Laakso et al 13 is not isodesmic, and, besides, the value used for ∆H , which does not compare very well with the DFT result. Since it is known that DFT approaches can not completely account for electronic correlation effects, the difference of about 6 kcal mol -1 found in these studies can only be explained by the level of theory employed.…”

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confidence: 89%

Enthalpy of Formation of CH3SO and CH3SO2: A Difficult Case in Quantum Chemistry

Resende

Ornellas

2002

J. Braz. Chem. Soc.

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As entalpias de formação do CH 3 SO e CH 3 SO 2 a 298,15 K foram determinadas num alto nível de correlação eletrônica, CCSD(T), e com o uso do procedimento de Woon e Dunning para se alcançar o limite de um conjunto de base completo. Este estudo forneceu valores de -16,7 kcal mol , respectivamente, para CH 3 SO e CH 3 SO 2 , que se espera serem os mais exatos até hoje. A análise dos cálculos existentes em vários níveis de teoria claramente mostra a necessidade de conjuntos de bases muito grandes e de um alto nível de tratamento da correlação eletrônica para se produzirem resultados confiáveis e exatos.The enthalpies of formation of CH 3 SO and CH 3 SO 2 at 298.15 K were determined at a high level of electronic correlation, CCSD(T), and with the use of Woon and Dunning's procedure to reach the complete basis set limit. This study led to values of -16.7 kcal mol -1 and -53.1 kcal mol -1 , respectively, for CH 3 SO and CH 3 SO 2 , which are expected to be the most accurate ones to date. Analysis of existing calculations at various levels of theory clearly shows the need of large basis sets and a high level of electronic correlation treatment to produce reliable and accurate results.

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“…Particularmente, o sistema molecular HSO 2 tem um papel relevante nestes processos climatológicos, além de formar parte de processos de combustão [86][87][88][89][90][91][92][93][94][95][96][97] .…”

Section: Sistemas Estudados Capítulo 4 4 Estudo De Trajetórias Qunclassified

“…O segundo é composto por poucos trabalhos que estudam a região da SEP de maiores energias [15,90,137] . E finalmente, o terceiro e último grupo é formado por trabalhos que têm sido voltados à descrição de estruturas estacionárias das duas regiões, incluindo as possíveis conexões entre elas [88,89,91,93,94,98,138] . O .…”

Section: Estudo Da Superfície De Energia Potencial Do Sistema Moleculunclassified

Fotofísica e propriedades dinâmicas de sistemas moleculares

González¹

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Theoretical studies of the RSOO, ROSO, RSO2 and HOOS (R=H, CH3) radicals

Cited by 38 publications

References 32 publications

Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO₂ and HS + O₂

Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO₂ and HS + O₂

Enthalpy of Formation of CH3SO and CH3SO2: A Difficult Case in Quantum Chemistry

Fotofísica e propriedades dinâmicas de sistemas moleculares

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Theoretical studies of the RSOO, ROSO, RSO2 and HOOS (R=H, CH3) radicals

Cited by 38 publications

References 32 publications

Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO2 and HS + O2

Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO2 and HS + O2

Enthalpy of Formation of CH3SO and CH3SO2: A Difficult Case in Quantum Chemistry

Fotofísica e propriedades dinâmicas de sistemas moleculares

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Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO₂ and HS + O₂

Characterization of Reaction Pathways on the Potential Energy Surfaces for H + SO₂ and HS + O₂