  The dynamics of the momentum distribution and the reduced single-particle
density matrix (RSPDM) of a Tonks-Girardeau (TG) gas is studied in the context
of Bragg-reflections of a many-body wavepacket. We find strong suppression of a
Bragg-reflection peak for a dense TG wavepacket; our observation illustrates
dependence of the momentum distribution on the interactions/wavefunction
symmetry. The momentum distribution is calculated with a fast algorithm based
on a formula expressing the RSPDM via a dynamically evolving single-particle
basis.
