Phonon damping model using random-phase-approximation operators

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 randomphase 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.