First characterization of sd-shell nuclei with a multiconfiguration approach

In this work, we propose a new description of nuclear spectroscopy based on the analysis of a rather complete set of observables, using the multiparticle-multihole configuration mixing and the D1S Gogny interaction. The application to the even-even sd-shell nuclei, for both ground and 0(2)(vertical bar), 1(1)(vertical bar), 2(1)(vertical bar), 2(2)(vertical bar), 3(1)(vertical bar), 3(2)(vertical bar), 4(1)(vertical bar) excited states, clearly shows the pertinence of this approach. The standard deviation to experiment is similar to 500 keV for two-nucleon separation energies and similar to 400 keV for excitation energies. The calculated magnetic dipole moments and B(M1) transition probabilities are in a very good agreement with experiment. Concerning the spectroscopic quadrupole moments and B(E2) transition probabilities, the experimental trends are systematically reproduced. Only a lack of quadrupole collectivity appears. A solution to improve this expected defect is suggested.