Computed energy profiles, at the different approaching angles of Figures 2–5, for the ﹩{{\rm{H}}}^{-}﹩ reaction with ﹩{\mathrm{HC}}_{2}{\rm{H}}﹩ (upper panels) and ﹩{\mathrm{HC}}_{4}{\rm{H}}﹩ (lower panel). The curves in the figures report the ﹩{{\rm{H}}}^{-}﹩ approaching the molecular partner from larger distances (right-hand part of the figures) and exiting as H₂ is formed at shorter distances: each curve refers to a different angle and each presents a minimum energy geometry of the complex (lower left side of the curves) after which the anion separates and the hydrogen molecule is formed. The coordinates of the separating products (see Figure 1) are not shown in this figure.