R. Polak et al., THEORETICAL CALCULATIONS OF THE QUARTET POTENTIAL-ENERGY SURFACES IN THE NH-2 SYSTEM( +H), Chemical physics, 178(1-3), 1993, pp. 245-253
The quartet potential energy surfaces of the NH+((4) Sigma(-))+H-2((1)
Sigma(g)(+)) system are studied using ab initio and DIM model calcula
tions. While there is a reaction path downhill towards H-3(+), the for
mation of NH2+(B-3(2)) seems to be characterized by a large activation
energy barrier. In C-2v configurations, the estimate for the energy b
arrier height was determined to be about 1.9 eV with respect to the en
ergy of the separated species. No substantial reduction of the barrier
height through symmetry relaxation could be found. A further typical
feature is that the quartet states exhibit a number of crossings with
low-lying doublet states, occurring mainly in the vicinity of the ener
gy barrier.