A PSDPF interaction to describe the 1 ℏω intruder states in sd shell nuclei

In the level schemes of sd shell nuclei, there is generally at relatively low excitation energies, coexistence of normal 0 ℏω positive parity states and of intruder 1 ℏω negative parity states. The aim of the present work is to describe these intruder states in the full p–sd–pf model space with a 4He core allowing one nucleon jump between the major shells. To construct our PSDPF interaction, we first modified the p–sd and sd–pf cross-monopole terms and then applied a fitting procedure to adjust all PSDPF parameters by comparing an extended set of experimental and calculated excitation energies. Results obtained with the new interaction have been finally compared with experimental data for nuclei throughout the sd shell.