Nuclear structure approach to the Coulomb correction of the imaginary nucleon-nucleus optical potential

The imaginary optical potentials for proton and neutron scattering have been calculated for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ using random phase approximation transition densities to describe intermediate states. Both inelastic and charge-exchange intermediate states are considered. The protons propagate in a nuclear-plus-Coulomb potential, and Coulomb excitation is included both for direct and exchange terms in the scattering amplitudes. Differences in the calculated neutron and proton optical potentials due to Coulomb excitation and isospin impurity of the random phase approximation states are found to be small. The expected exclusion of high-lying intermediate states by the Coulomb potential is present but it is compensated by a larger proton wave function in positive kinetic energy regions and by a more favorable local equivalent potential for protons.