Many-body theory of effective local potentials for electronic excitations. III. Application to giant dipole resonances

The 4d{→}f transitions in Xe and Ba and the 4p{→}d transition in Kr are analyzed in terms of the effective wave functions and effective local potentials in an energy region where the response of the system is highly resonant and shows collective behavior. The effective potentials are obtained in the random-phase approximation with exchange, and the importance of relaxation is investigated. It is found that the energy dependence of the effective potential is necessary to describe the excitation spectrum reasonably well. The effects of external screening by adding and removing electrons (Ba^1--Ba²⁺) are analyzed and the applicability of the atomiclike model for the 4d{→}f transitions in metallic Ba is discussed.