Singlet–triplet energy gap for trimethylenemethane, oxyallyl diradical, and related species: single- and multireference computational results

Saitô, Tôru; Nishihara, Satomichi; Yamanaka, Shusuke; Kitagawa, Yasutaka; Kawakami, Takashi; Yamada, Satoru; Isobe, Hiroshi; Okumura, Mitsutaka; Yamaguchi, Kizashi

doi:10.1007/s00214-011-0914-z

Cited by 33 publications

(29 citation statements)

References 58 publications

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“…Table I compares the singlet-triplet splittings predicted by different approximations with experimental data for a set of particularly challenging benchmarks [49][50][51][52] including small diatomics, 53 methylene, 54 trimethylenemethane, 55 and benzyne isomers. 56 Here, UHF+TPSS data are also given for comparison purposes; while it improves upon UHF, SUHF+TPSS techniques roughly halve the mean average error (MAE) of UHF+TPSS.…”

Section: B Singlet-triplet Splittingsmentioning

confidence: 99%

Capturing static and dynamic correlations by a combination of projected Hartree-Fock and density functional theories

Garza

Jiménez-Hoyos

Scuseria

2013

The Journal of Chemical Physics

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This paper explores the possibility of combining projected Hartree-Fock and density functional theories for treating static and dynamic correlations in molecular systems with mean-field computational cost. The combination of spin-projected unrestricted Hartree-Fock (SUHF) with the TPSS correlation functional (SUHF+TPSS) yields excellent results for non-metallic molecular dissociations and singlet-triplet splittings. However, SUHF+TPSS fails to provide the qualitatively correct dissociation curve for the notoriously difficult case of the chromium dimer. By tuning the TPSS correlation parameters and adding complex conjugation symmetry breaking and restoration to SUHF, the right curve shape for Cr 2 can be obtained; unfortunately, such a combination is found to lead to overcorrelation in the general case.

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Section: B Singlet-triplet Splittingsmentioning

confidence: 99%

Capturing static and dynamic correlations by a combination of projected Hartree-Fock and density functional theories

Garza

Jiménez-Hoyos

Scuseria

2013

The Journal of Chemical Physics

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“…Typical examples of stable biradicals consist of organic molecules in which the two lone electrons are well-separated from each other. A typical example of an organic biradical is trimethylenemethane (TMM), C(CH 2 ) 3 , for which ESR measurements suggested a triplet ground state of D 3h symmetry [7] and a singlet first excited state [8] of C 2v symmetry as a result of a Jahn-Teller distortion lying (16.1 AE 0.1) kcal mol À1 above it. A typical example of an organic biradical is trimethylenemethane (TMM), C(CH 2 ) 3 , for which ESR measurements suggested a triplet ground state of D 3h symmetry [7] and a singlet first excited state [8] of C 2v symmetry as a result of a Jahn-Teller distortion lying (16.1 AE 0.1) kcal mol À1 above it.…”

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confidence: 99%

Unusual Inorganic Biradicals: A Theoretical Analysis

Miliordos,

Ruedenberg,

Xantheas

2013

Angewandte Chemie

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Der Biradikal‐Charakter β (mit 1 für ein ideales Biradikal) wird aus Multireferenz‐Konfigurationswechselwirkungs(MRCI)‐Wellenfunktionen bestimmt. Für die dreiatomigen Ionen der Reihe FX2+ (X=O, S, Se, Te, Po) ergeben sich mit 0.76–0.92 die höchsten β‐Werte unter den homologen 18‐Valenzelektronen‐Molekülen, verglichen mit CX22−, NX2−, X3 und OX2. Auf derselben Skala beträgt der Biradikal‐Charakter von O3 lediglich 0.19, C(CH2)3 erreicht hingegen einen Wert von 0.97.

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“…More work is required to computationally describe this reaction in detail, preferably by using multi-reference methods to accurately describe state mixing. [46] Kinetic modelling A kinetic model was set up in Matlab by using the ODE15s solver for stiff ordinary differential equations (ODEs). The initial conditions for solving the ODEs were obtained from experimental data.…”

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confidence: 99%

Peculiarities of β‐Pinene Autoxidation

2011

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The thermal oxidation of the renewable olefin β-pinene with molecular oxygen was experimentally and computationally investigated. Peroxyl radicals abstract weakly bonded allylic hydrogen atoms from the substrate, yielding allylic hydroperoxides (i.e., myrtenyl and pinocarvyl hydroperoxide). In addition, peroxyl radicals add to the C=C bond of the substrate to form an epoxide. It was found that a relatively high peroxyl radical concentration, together with the high rate of peroxyl cross-reactions, make radical-radical reactions surprisingly important for this particular substrate. Approximately 60 % of these peroxyl cross-reactions lead to termination (radical destruction), keeping a radical chain length of approximately 4 at 10 % conversion. Numerical simulation of the reaction-based on the proposed reaction mechanism and known or predicted rate constants-demonstrate the importance of peroxyl cross-reactions for the formation of alkoxyl radicals, which are the precursor of alcohol and ketone products.

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Singlet–triplet energy gap for trimethylenemethane, oxyallyl diradical, and related species: single- and multireference computational results

Cited by 33 publications

References 58 publications

Capturing static and dynamic correlations by a combination of projected Hartree-Fock and density functional theories

Capturing static and dynamic correlations by a combination of projected Hartree-Fock and density functional theories

Unusual Inorganic Biradicals: A Theoretical Analysis

Peculiarities of β‐Pinene Autoxidation

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