Effect of correlations in ground state and elastic scattering nucleon on nuclei $^{16}$O and $^{40}$Ca

In the present article, the imaginary part of the optical potential is studied, in light of contributions from an inelastic channel along with excitation of cooperative levels. The computation of Im Vopt is carried out under the assumptions of the Tamm-Dankov and random phase approximations. It is shown that the contribution of the lower cooperative levels (which yield the basic contribution to Im Vopt)is much greater in the random phase approximation than is the Tamm-Dankov approximation. Particular computations are performed for ${16}^$O and ${40}^Ca nuclei.