Large basis ab initio shell model investigation of 9Be and 11Be

摘要: We present the first ab initio structure investigation of loosely bound $^{11}\mathrm{Be}$ nucleus, together with a study lighter isotope $^{9}\mathrm{Be}$. The nuclear these isotopes is particularly interesting because appearance parity-inverted ground state in $^{11}\mathrm{Be}$. Our performed framework no-core shell model. Results obtained using four different, high-precision two-nucleon interactions, model spaces up to $9\ensuremath{\hbar}\ensuremath{\Omega}$, are shown. For both nuclei, and all potentials, we reach convergence level ordering positive- negative-parity spectra separately. Concerning their relative position, positive-parity states always too high excitation energy, but fast drop respect spectrum observed when space increased. This behavior most dramatic for In largest were able reach, $1/{2}^{+}$ has dropped down become either or second excited state, depending on which interaction use. also observe contrasting patterns different potentials argue that three-nucleon needed explain parity inversion. Furthermore, large-basis calculations $^{13}\mathrm{C}$ $^{11}\mathrm{B}$ performed. allows us systematics position unnatural-parity $N=7$ isotone $A=11$ isobar. run $9\ensuremath{\hbar}\ensuremath{\Omega}$ involves matrix dimension exceeding $1.1\ifmmode\times\else\texttimes\fi{}{10}^{9}$, our calculation so far. results binding energies, spectra, configurations, radii, electromagnetic observables, $^{10}\mathrm{Be}+n$ overlap functions.