Theoretical characterization of the potential energy surface for H+N2→HN2. II. Computed points to define a global potential.

A previous calculation for H+N2 [Walch, Duchovic, and Rohlfing, J. Chem. Phys. 90, 3230 (1989)] focused on the minimum energy path (MEP) region of the potential energy surface and on estimates of the lifetime of the HN2 species. In this paper, we report energies computed at geometries selected to permit a global representation of the potential energy surface (PES). As in the previous work, the calculations were performed using the complete active space self-consistent field/externally contracted configuration interaction (CASSCF/CCI) method. The surface was characterized using the same basis set as in the previous paper except that an improved contraction of the H s basis is used. Calculations with a larger basis set were carried out along an approximate MEP obtained with the smaller basis set. The new PES exhibits a sharp curvature, which was not present in the previous calculations, and has a slightly narrower and smaller barrier to dissociation. Saddle points for H atom exchange via collinear and T-shaped HN2 complexes are also reported. [ABSTRACT FROM AUTHOR]