Low-Energy E1 Strength Distributions of $^{68}$Ni

International audienceWe study the effects of the coupling between one- and two-phonon components of the wave functions on the low-energy electric dipole response of$^{68}$Ni in a microscopic model based on an effective Skyrme interaction SLy5. The finite rank separable approach for the quasiparticle random phase approximation is used. The effect of phonon-phonon coupling leads to the fragmentation of the $E1$ strength to a lower energy and improves the agreement with available experimental data