Competition between abstraction and exchange channels in H + HCN reaction: full-dimensional quantum dynamics. 
Dynamics of the title reaction is investigated on an ab initio based potential energy surface using a full-dimensional quantum wave packet method within the centrifugal sudden approximation.  It is shown that the reaction between H and HCN leads to both the hydrogen exchange and hydrogen abstraction channels.  The exchange channel has a lower threshold and larger cross section than the abstraction channel.  It also has more oscillations due apparently to quantum resonances.  Both channels are affected by long-lived resonances supported by potential wells.  Comparison with experimental cross sections indicates underestimation of the abstraction barrier height.