A fully microscopic interpretation of the phonon damping model (PDM) is proposed. The phonon operator, which generates the collective excitation such as giant dipole resonance (GDR), is constructed from coherent particle-hole pairs. The phonon energy is determined as the solution of dispersion equation within the random-phase approximation (RPA). The phonon structure is found in term of RPA X and Y amplitudes. The formalism is illustrated by numerical calculations within a schematic model. The results of calculations demonstrate the same feature of GDR as a function of temperature obtained previously within PDM-1, which employs structureless phonons.

• Received 9 January 2001

DOI:https://doi.org/10.1103/PhysRevC.64.024302