  We analyze the dynamics of two atoms with a short-ranged pair interaction in
a one-dimensional harmonic trap with time-dependent frequency. Our analysis is
focused on two representative cases: (i) a sudden change of the trapping
frequency from one value to another, and (ii) a periodic trapping frequency. In
case (i), the dynamics of the interacting and the corresponding non-interacting
systems turn out to be similar. In the second case, however, the interacting
system can behave quite differently, especially close to parametric resonance.
For instance, in the regions where such resonance occurs we find that the
interaction can significantly reduce the rate of energy increase. The
implications for applications of our findings to cool or heat the system are
also dicussed.
