Positive parity states in ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$

The low-lying positive parity states of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$ are calculated in a coupled channels treatment of a valence neutron interacting with a deformed core. The loosely bound nature of the valence neutron is taken into account by using a Woods-Saxon potential. Comparisons are made to shell-model predictions and to data. The model reproduces the measured spectrum quite well for realistic parameters of the neutron-core interaction.