Details

Autor(en) / Beteiligte

• Peters, Phillip S
• Duflot, Denis
• Wiesenfeld, Laurent
• Toubin, Céline

Titel

The H + CO ⇌ HCO reaction studied by ab initio benchmark calculations

Ist Teil von

• The Journal of chemical physics, 2013-10, Vol.139 (16), p.164310-164310

Ort / Verlag

United States: American Institute of Physics

Erscheinungsjahr

2013

Quelle

AIP Journals Complete

Beschreibungen/Notizen

• The title reaction has been calculated using complete active space self-consistent field and internally contracted multi-reference configuration interaction, including Davidson correction, calculations. Dunning's correlation consistent atomic basis sets, together with several complete basis set extrapolation schemes, were employed. Core-valence and scalar relativistic effects were also taken into account, as well as anharmonicity of the vibrational modes. Core-valence correlation appears to have a large impact on the calculated frequencies, spectroscopic constants, and on the energetics. In particular, the best estimate for the HCO (DCO) formation barrier height at 0 K, 4.54 ± 0.14 (4.43 ± 0.14) kcal mol(-1) is larger than previous theoretical works and well above the usually accepted value of 2.0 ± 0.4 kcal mol(-1), measured at room temperature. Inclusion of temperature and entropy at 298 K does not seem to be able to solve this discrepancy. The present theoretical barrier height is therefore the recommended value. The exo-ergicity of the HCO (DCO) dissociation reaction, predicted to be -13.36 ± 0.57 (-14.72 ± 0.57) kcal mol(-1), is slightly below the experimental value. Finally, all tested density functionals fail to reproduce accurately both the formation and dissociation barriers.