Abstract
A correlated ground state of ^40Ca and an isoscalar E2 giant resonance built on it are calculated using an extended version of the time-dependent Hartree-Fock theory known as the time-dependent density-matrix theory (TDDM). The Skyrme III force is used as an effective interaction for the calculation of both a mean field and two-body correlations. It is found that, although a TDDM calculation with the Skyrme force gives reasonable ground-state correlations, the calculated spreading width of the E2 giant resonance is small as compared with experiments. A double phonon state of the E2 giant resonance is also studied in TDDM. It is found that the double phonon state calculated in TDDM has properties of the double phonon states of the E2 resonance calculated in the random phase approximation.
