Effect of classically forbidden momenta in one dimensional quantum   scattering
  The transmitted wave that results from a collision of a wave packet which is initially to the left of a potential barrier depends in general on the amplitudes of negative momenta of the initial state. The exact form of this dependence is shown and the importance of this classically forbidden effect is illustrated with numerical examples. Special care is taken to account properly for bound states. 
A. D. Baute, I. L. Egusquiza and J. G. Muga