Structure and potential energy surface for Na⁺．N₂

Abstract

Attention is focused on the Na⁺．N₂complex as part of a study of Na⁺-containing complexes, which have been implicated in the formation of sporadic sodium layers in the upper atmosphere. The equilibrium structure is found to be linear, in agreement with previous studies. A potential energy hypersurface is calculated at the CCSD(T)/aug-cc-pVTZ level of theory, where the N₂ moiety is held fixed, but a wide range of Jacobi bond lengths and bond angles are sampled. This hypersurface is fitted to an analytic form and from this anharmonic vibrational separations are calculated, and compared to harmonic values. Rovibrational energy levels are also calculated from the fitted hypersurface. The best estimate of the interaction energy, ΔEₑ is 2770 cm⁻¹, and ΔH[sub f]²⁹⁸(Na⁺．N₂)=(136.5± 2.0) kcal mol⁻¹.