New effective interaction for0ℏωshell-model calculations in thesd−pfvalence space

The neutron-rich isotopes with $Z\ensuremath{\leqslant}20$, in particular those with neutron numbers around $N=28$, have been the focus of a lot experimental and theoretical scrutiny during the past few years. Shell-model calculations using the effective interaction SDPF-NR were able to predict or to explain most of the properties featured by these nuclei. Prominent among them is the disappearance of the $N=28$ shell closure for $Z\ensuremath{\leqslant}16$. We have incorporated into SDPF-NR some modifications, either on purely theoretical grounds or guided by new experimental information. The proposed interaction SDPF-U offers enhanced reliability with respect to the earlier version.