Comparison of a bound state scattering calculation with a quantum chemistry-style calculation as described in the text for m ^{1}A_g symmetry

Figure 2. Comparison of a bound state scattering calculation with a quantum chemistry-style calculation as described in the text for \rm ^{1}A_g symmetry. As this is a calculation in the lower symmetry group D_2h, states with symmetries \rm ^1 \Sigma ^+_g, \rm ^1 \Delta _g and \rm ^1 \Gamma _g all appear on this plot. Spurious data points have been removed. Note that for the lower-lying states the scattering and quantum chemistry-style results coincide.

Abstract

Potential energy curves for electronically excited states of molecular nitrogen are calculated using three different ab initio procedures. The most comprehensive of these involves the use of scattering calculations, performed at negative energy using the UK molecular R-matrix method. Such calculations are used to characterize all the Rydberg states of N₂ with n ≤ 6 and ℓ ≤ 4 as well as many higher states including some Rydberg states associated with the first excited A ²Π_u state of N_2^+. Many of these states are previously unknown. The calculations are performed at a dense grid of internuclear separations allowing the many avoided crossings present in the system to be mapped out in detail. Extensive comparisons are made with the previously available data for excited states of N₂.