TY - JOUR
T1 - An assessment of the performance of high-level theoretical procedures in the computation of the heats of formation of small open-shell molecules
AU - Henry, David J.
AU - Parkinson, Christopher J.
AU - Radom, Leo
PY - 2002/8/29
Y1 - 2002/8/29
N2 - The heats of formation at 0 K (ΔfH0) of 29 small (containing up to 3 heavy atoms) open-shell molecules, with accurately known experimental values, have been calculated using a number of high-level theoretical procedures. The theoretical methods examined include variants of Gaussian-n (G2, G2-RAD(RMP2), G2-RAD(B3-LYP), G2-RAD(QCISD), G3, G3-RAD, G3X, G3X-RAD, G3(MP2), G3(MP2)-RAD, G3X(MP2) and G3X(MP2)-RAD), CBS (CBS-APNO, CBS-Q, CBS-RAD and CBS-QB3), and Martin extrapolation (Martin-2, Martin-3, W1, W1′, W1h, W2h and W2) procedures. The open-shell systems include doublet radicals (·BeH, ·CH, ·CH3, ·NH2, ·OH, ·SiH3, ·PH2, ·SH, ·N2+, ·NO, ·ONO, ·O2-, ·CN, ·CO+,·CS+, ·CCH, ·CHO, ·OOH, ·CHCH2, ·CH2CH3, ·CH2OH, ·OCH3, ·SCH3 and ·COCH3) and triplet biradicals (:CH2, :NH, :SiH2, :O2, and :S2). The results for these systems are used to assess the performance of the various theoretical methods. The smallest mean absolute deviations (MADs) from experiment are found with the G3-RAD, G3X-RAD, G3X, W1h, W2, W1, and W2h procedures with MADs lying in the range 2.0-2.5 kJ mol-1 The smallest values for the largest deviation (LD) from experiment are found with the G3X, G3X-RAD, W2, and W2h procedures and are ±6.4 kJ mol-1. A selection of the most accurate theoretical procedures (G3-RAD, G3X-RAD, G3X, W1h, W2, W1, and W2h) is used to predict the heats of formation for several radicals (·OF, ·CH2CHCH2, ·CH2CN, ·CH2COOH, and ·CH2C6H5) for which there are greater uncertainties associated with the experimental values.
AB - The heats of formation at 0 K (ΔfH0) of 29 small (containing up to 3 heavy atoms) open-shell molecules, with accurately known experimental values, have been calculated using a number of high-level theoretical procedures. The theoretical methods examined include variants of Gaussian-n (G2, G2-RAD(RMP2), G2-RAD(B3-LYP), G2-RAD(QCISD), G3, G3-RAD, G3X, G3X-RAD, G3(MP2), G3(MP2)-RAD, G3X(MP2) and G3X(MP2)-RAD), CBS (CBS-APNO, CBS-Q, CBS-RAD and CBS-QB3), and Martin extrapolation (Martin-2, Martin-3, W1, W1′, W1h, W2h and W2) procedures. The open-shell systems include doublet radicals (·BeH, ·CH, ·CH3, ·NH2, ·OH, ·SiH3, ·PH2, ·SH, ·N2+, ·NO, ·ONO, ·O2-, ·CN, ·CO+,·CS+, ·CCH, ·CHO, ·OOH, ·CHCH2, ·CH2CH3, ·CH2OH, ·OCH3, ·SCH3 and ·COCH3) and triplet biradicals (:CH2, :NH, :SiH2, :O2, and :S2). The results for these systems are used to assess the performance of the various theoretical methods. The smallest mean absolute deviations (MADs) from experiment are found with the G3-RAD, G3X-RAD, G3X, W1h, W2, W1, and W2h procedures with MADs lying in the range 2.0-2.5 kJ mol-1 The smallest values for the largest deviation (LD) from experiment are found with the G3X, G3X-RAD, W2, and W2h procedures and are ±6.4 kJ mol-1. A selection of the most accurate theoretical procedures (G3-RAD, G3X-RAD, G3X, W1h, W2, W1, and W2h) is used to predict the heats of formation for several radicals (·OF, ·CH2CHCH2, ·CH2CN, ·CH2COOH, and ·CH2C6H5) for which there are greater uncertainties associated with the experimental values.
UR - http://www.scopus.com/inward/record.url?scp=0037194948&partnerID=8YFLogxK
U2 - 10.1021/jp0260752
DO - 10.1021/jp0260752
M3 - Article
SN - 1089-5639
VL - 106
SP - 7927
EP - 7936
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 34
ER -