Ab initio potential surfaces for the atomic oxygen(1D) + methane reaction

Abstract

The interaction potentials between O(lD) and methane and the potential surface for the reaction have been calculated by the ab initio MRDCI method. The minimum energy path of the reaction is an almost collinear approach of O(lD) to one of the hydrogen atoms of methane up to the position of rOH = 1.66 A. A very low potential barrier (2.1 kcal mol-') exists along the path, and then the oxygen atom migrates off-axis. The surface correlates to the stable methanol structure. The product channel to yield CH3 + O H and also the one to yield CH3O + H are both directly derived from the potential minimum corresponding to the stable methanol structure without any exit potential barriers. Possible reaction dynamics on the surface are discussed.

Product Branching Ratios for O(3P) Atom and ClO Radical Formation in the Reactions of O(1D) with Chlorinated Compounds

“…Thus Φ q values for O( 1 D) + HFCs drastically decrease when F atoms in HFCs are substituted by H atoms. This consideration is consistent with the suggested mechanism [37][38][39][40] …”

CH3 state distributions form the reactions of O(1D) with saturated and chlorinated hydrocarbons

“…6 The reaction surface of the lowest singlet state was calculated for 90 different sets of C-O and C-H distances with a full optimization of the remaining degrees of freedom within the framework of C s symmetry. According to this surface, O͑ 1 D͒ approaches one of the C-H bonds collinearly with only a small barrier of 8.8 kJ mol Ϫ1 and a very similar geometry of the CH 4 moiety as in the stable CH 4 , at the saddle point.…”

“…ence single and double CI method. 6 The surface is calculated along the CO and CH distance with otherwise optimized geometries in C s symmetry. From the surface, one can qualitatively learn about the umbrella motion of the CH 3 moiety and the CH stretch motion from their respective potential gradients during the reaction.…”

Rotational spectral studies of O(1D) insertion reactions with methane and ethylene: Methanol and vinyl alcohol in a supersonic expansion

“…This reaction has been studied extensively through both experimental and theoretical [42][43][44][45][46][47][48] methods. An energy diagram showing an overview of the insertion reaction and subsequent dissociation pathways is shown in Figure 1.…”