  We consider the evolution of two contact-interacting harmonically-trapped
particles following an arbitrary quench in interaction strength. We calculate
the post-quench particle separation as a function of time and the total
post-quench energy. When quenching from any non-zero interaction strength to
zero interaction strength we observe that the total energy and particle
separation diverge. In particular, the divergent behaviour arises always and
exclusively when quenching to the non-interacting regime. The source of the
divergence is a power-law tail in the probability distribution of particle
separation. This validates and builds upon previous work that found divergent
behaviour arises when quenching from the strongly interacting limit to the
non-interacting limit in both the two and three-body cases.
