In. Mikhailov et al., DAMPING OF NUCLEAR COLLECTIVE MOTIONS WITHIN THE METHOD OF PHASE-SPACE MOMENTS OF THE WIGNER DISTRIBUTION FUNCTION, Nuclear physics. A, 575(2), 1994, pp. 269-282
The semiclassical method of the equations of motion for the phase-spac
e moments of the Wigner function is extended to the inclusion of dampi
ng mechanisms. The gross structure of the strength function is obtaine
d going beyond the scaling approximation. Two-body correlations are in
troduced through an extended relaxation-time approximation. A realisti
c Skyrme-type interaction is used to derive the self-consistent potent
ial. An application is shown to the damping of the giant monopole reso
nance (GMR) in Pb-208. The calculated spreading widths with a relaxati
on-time parameter determined microscopically for the ''collisional'' d
amping are very much below the observed values. On the other side, con
sistency is found between the description of the widths of monopole, q
uadrupole and octupole giant resonances with an empirical value of the
relaxation-time parameter.