Giant dipole resonance in neutron-rich nuclei within the phonon damping model

The damping of the giant dipole resonance (GDR) in neutron-rich nuclei ${}^{18,24}\mathrm{O},$ ${}^{60}\mathrm{Ca},$ and ${}^{150}\mathrm{Sn}$ is calculated within the phonon damping model (PDM) and compared with those in $\ensuremath{\beta}\ensuremath{-}$stable isotopes. The Hartree-Fock single-particle energies obtained employing the SGII interaction are used in calculations. The PDM parameter for the $\mathrm{ph}$-phonon interaction between the levels close to the Fermi surface in exotic nuclei has been chosen to simulate the strong coupling between the GDR phonon and dense incoherent $\mathrm{ph}$ configurations. The results of the calculations show the appearance of a low-lying structure (pigmy resonance) in all exotic nuclei under consideration. The calculations at nonzero temperature show that the GDR in hot medium and heavy neutron-rich nuclei exhibits a similar behavior as those of the hot GDR in stable nuclei. The pigmy resonance is smoothed out with increasing temperature.