Reaction Promoted by Libration
127 cm-1 ag-libration around the long molecular axis. This is the lowest energy intermolecular mode promoting the reaction. Note the decrease of the H···N distance (white/blue) due to the motion.
Excite and start the reaction.
In addition to this intermolecular mode two further low energy intramolecular modes at 95 and 238 cm-1 can promote the tunneling reaction.