Ab initio potential energy surfaces for triplet states of NH₂⁺

Abstract

Ab initio configuration interaction calculations using Dunning's basis set augmented with polarization functions are presented for the ³Σ^-, ³ A ₂, ³ B ₁, and ³ A″ surfaces for the reactions N⁺ + H₂ and N + H₂ ⁺. The inclusion of polarization functions has little effect on the potential minima for the ³Σ^- and ³ B ₁ surfaces in contrast to the ³ A ₂ surface. Surfaces of C _∞v and C _2v symmetry correlate as follows: ³Σ^--1³ A″-³ A ₂, ³Π-2³ A″-³ B ₁. For collinear and near collinear collisions the reaction N⁺ + H₂ is expected to occur by a direct mechanism on the ³Σ^--1 ³ A″ surfaces. For C _2v geometries motion will occur on the ³ A ₂ surface which has a well depth of 2·6 eV. A low energy route to the deep potential well of ³ B ₁ NH₂ ⁺ is possible for C _δ collisions of near C _2v geometry. Te triplet surfaces correlating with N + H₂ ⁺ are repulsive and reaction at low energies is unlikely to occur on these surfaces.