Compressional and toroidal dipole modes in nuclei

We studied the nuclear electric isoscalar dipole response in proton–neutron random-phase approximation using different separable Hamiltonians and carried out a detailed comparison with the available experimental data. The analysis of the response to the different pieces of the Hamiltonian has disclosed properties of the compressional dipole mode not directly accessible to previous realistic approaches and, thereby, has identified some of the reasons of the discrepancies between these calculations and the experiments. In this perspective we have also studied the structure of the toroidal operator, its relation to the pure and compressional dipole fields, and computed its contribution to the dipole response.