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RESEARCH PRODUCT
An Ab Initio Study on the Mechanism of the Atmospheric Reaction NH2+O3→H2NO+O2
Manuela MerchánJulio Peiró-garcíaIgnacio Nebot-gilsubject
Reaction mechanismHypersurfaceChemistryAb initio quantum chemistry methodsEnthalpyAb initioPhysical chemistryPhysical and Theoretical ChemistryPotential energyChemical reactionAtomic and Molecular Physics and OpticsTransition statedescription
The atmospheric reaction NH 2 +0 3 →H 2 NO+O 2 has been investigated theoretically by using MP2, QCISD, QCISD(T), CCSD(T), CASSCF, and CASPT2 methods with various basis sets. At the MP2 level or theory, the hypersurface of the potential energy (HPES) shows a two step reaction mechanism. Therefore, the mechanism proceeds along two transition states (TS1 and TS2), seperated by an intermediate disignated as Int. However, when the single-reference higler correlated QCISD and the multiconfigurational CASSCF methodologies have been employed, the minimum structure Int and TS2 are not found on the HPES, which thus confirms a direct reaction mechanism. Single-reference high correlated and multiconfigurational methods consistently predict the barrier height of the reaction to be within the range of 3.9 to 6.6 kcal mol -1 , wich is somewhat higher than the experiemntal value. The calculated reaction enthalpy is - 67.7 kcal mol -1 .
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2003-05-06 | ChemPhysChem |