TY - JOUR
T1 - Ab initio molecular orbital study of potential energy surface for the reaction of C 2H 3 with H 2 and related reactions
AU - Mebel, Alexander M.
AU - Morokuma, Keiji
AU - Lin, Ming-Chang
PY - 1995/9
Y1 - 1995/9
N2 - The potential energy surface of the reaction C 2H 3+H 2→C 2H 4+H→C 2H 5 has been investigated using various theoretical methods including QCISD(T), CCSD(T), RCCSD(T), Gaussian-2 (G2), and the density-functional B3LYP approach. The reaction of the vinyl radical with molecular hydrogen is shown to take place through the hydrogen atom abstraction channel leading to the formation of C 2H 4+H with the activation energy of 10.4 kcal/mol at all the G2, QCISD(T)/ 6-311+G(3df,2p), and CCSD(T)/6-311+G(3df/,2p) levels. The rate constant, calculated using the variational transition state theory with tunneling correction, k=3.68·10 -20·T 2.48·exp(-3587/T) cm 3 molecule -1 s -1, is in good agreement with the experimental estimates. C 2H 5 cannot be formed directly by inserting C 2H 3 to H 2, but can only be produced by addition of H to C 2H 4, with a barrier of 4.5-4.7 kcal/mol calculated at high levels of theory. In order to match the experimental rate constant, the activation energy needs to be adjusted to 2.8 kcal/mol. Generally, the B3LYP method is found to predict well the geometries and vibrational frequencies of various species. However, it is less reliable for energy calculations than the QCISD(T) and CCSD(T) methods.
AB - The potential energy surface of the reaction C 2H 3+H 2→C 2H 4+H→C 2H 5 has been investigated using various theoretical methods including QCISD(T), CCSD(T), RCCSD(T), Gaussian-2 (G2), and the density-functional B3LYP approach. The reaction of the vinyl radical with molecular hydrogen is shown to take place through the hydrogen atom abstraction channel leading to the formation of C 2H 4+H with the activation energy of 10.4 kcal/mol at all the G2, QCISD(T)/ 6-311+G(3df,2p), and CCSD(T)/6-311+G(3df/,2p) levels. The rate constant, calculated using the variational transition state theory with tunneling correction, k=3.68·10 -20·T 2.48·exp(-3587/T) cm 3 molecule -1 s -1, is in good agreement with the experimental estimates. C 2H 5 cannot be formed directly by inserting C 2H 3 to H 2, but can only be produced by addition of H to C 2H 4, with a barrier of 4.5-4.7 kcal/mol calculated at high levels of theory. In order to match the experimental rate constant, the activation energy needs to be adjusted to 2.8 kcal/mol. Generally, the B3LYP method is found to predict well the geometries and vibrational frequencies of various species. However, it is less reliable for energy calculations than the QCISD(T) and CCSD(T) methods.
UR - http://www.scopus.com/inward/record.url?scp=36849098548&partnerID=8YFLogxK
U2 - doi.org/10.1063/1.470715
DO - doi.org/10.1063/1.470715
M3 - Article
AN - SCOPUS:36849098548
SN - 0021-9606
VL - 103
SP - 3440
EP - 3449
JO - The Journal of chemical physics
JF - The Journal of chemical physics
IS - 9
ER -