Parity inversion and breakdown of shell closure in Be isotopes

The coupling of single-particle motion and of vibrations in 411Be produces dressed neutrons which spend only a fraction of the time in pure single-particle states, and which weighing differently from the bare neutrons lead to parity inversion. The interaction of the two least bound neutrons in the ground state of 412Be mediated by the v14 Argonne nucleon-nucleon potential and by the exchange of surface vibrations of the core 10Be gives rise to a strongly correlated state, where the two valence neutrons are distributed over s2,p2, and d2 configurations, resulting in the breaking of the N=8 shell closure.