  The mechanism of collectivity coexisting with chaos is investigated on the
quantum level. The complex spectra are represented in the basis of two-particle
two-hole states describing the nuclear double-charge exchange modes in
$^{48}$Ca. An example of $J^{\pi}=0^-$ excitations shows that the residual
interaction, which generically implies chaotic behavior, under certain specific
and well identified conditions may create transitions stronger than those
corresponding to the pure mean-field picture. Therefore, for this type of
excitations such an effect is not generic and in most cases the strength of
transitions is likely to take much lower values, even close to the
Porter-Thomas distributed.
