The 95 and 238 cm-1 reaction promoting modes from the NCA calculation [56]. The table on right shows the vibrational H-displacement for n = 1. The values for ½Dr½ and the projection along the C···N direction are given in Å. From this modes around 440 cm-1 do not promote the reaction. The missing second harmonic of the libration and the appearance of E2 at 440 cm-1 in the reaction rate can be due to phase correlated interference effects.