Calculated barrier heights for OH + C/sub 2/H/sub 2/ and OH + C/sub 2/H/sub 4/ using unrestricted Moeller-Plesset perturbation theory with spin annihilation
The reactions of OH radical with C/sub 2/H/sub 2/ and C/sub 2/H/sub 4/ have been studied with ab initio molecular orbital techniques. Reactants, loose clusters, transition structures, and products were optimized at UHF/3-21G and UHF/6-31G*. The barrier heights have been computed by using unrestricted Hartree-Fock and Moeller-Plesset perturbation theory up to fourth order, including single, double, and quadruple excitations. Spin contamination in the UHF wave function has been corrected by annihilating the largest spin contaminant. The vibrational frequencies were computed by using analytical derivative methods at the UHF/3-21G level. The barrier heights for both reactions are overestimated by 7-15 kcal/mol at the UMP2, UMP3, and UMP4 levels. Annihilation of the largest spin contaminant lowers the barrier heights by 7-15 kcal/mol. Calculations at the PMP4/6-31G* level are in good agreement with the estimated experiment barrier heights.
- Research Organization:
- Wayne State Univ., Detroit, MI
- OSTI ID:
- 5954146
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 109:14
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
ACETYLENE
CHEMICAL REACTIONS
ETHYLENE
HYDROXYL RADICALS
HARTREE-FOCK METHOD
MOLECULAR MODELS
MOLECULAR ORBITAL METHOD
THEORETICAL DATA
ALKENES
ALKYNES
DATA
HYDROCARBONS
INFORMATION
MATHEMATICAL MODELS
NUMERICAL DATA
ORGANIC COMPOUNDS
RADICALS
400201* - Chemical & Physicochemical Properties
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