R. Polak et al., THEORETICAL-MODEL AND ABINITIO CALCULATION OF POTENTIAL-ENERGY SURFACES FOR THE REACTION NH-PI)+H-2(1-SIGMA-G+)( .(2), Chemical physics, 172(1), 1993, pp. 73-83
This paper examines the doublet potential energy surfaces (PESs) gover
ning the NH+(H-2)-->NH2+(H) reaction by combining ab initio calculatio
ns of the PES with a model Hamiltonian. It appears that in C2v ColliSi
ons, the deep ground-state minimum is separated from the reactants by
a barrier of about 1.2 eV. In the region around the barrier , several
PESs exhibit crossings which become avoided for lower symmetry. Thus,
in this region low energy paths between reactants and products can ari
se which do not necessarily sample the deep minimum of the ground stat
e. These paths, together with possible non-adiabatic transitions, can
therefore account for the experimentally observed behaviour of the rea
ction.