Ab Initio Molecular Orbital Calculations of the Potential Energy Surfaces for the N(²D) + CH₄ Reaction

Ab initio molecular orbital calculations have been carried out on the N( 2 D) + CH 4 reaction in order to obtain information on possible reaction products. Stationary points associated with the product channels and their harmonic vibrational frequencies have been calculated at the MP2(full)/cc-pVTZ level of theory. Barrier heights and heats of reaction have been estimated at the projected MP4(full,SDTQ)/cc-pVTZ level of theory. Among the possible processes considered, the reaction pathways to produce CH 2 NH + H and CH 3 + NH have been found to be important. RRKM calculations have been performed to confirm this result. The saddle point structure in the entrance channel of the N( 2 D) + CH 4 reaction has also been calculated using the CASSCF method. It has been found that N( 2 D) inserts into the C−H bond of CH 4, which is qualitatively consistent with recent experimental results.