Deformation effects on the structures of N=7 halo nuclei

The structures of N=7 isotones have been investigated using the deformed Skyrme–Hartree–Fock model. The approximate particle number projection by means of the Lipkin–Nogami method was used with the blocking effect of the odd neutron taken into account. For nuclei near the drip lines, a volume–surface mixing pairing interaction was employed, which can well reproduce odd–even differences for the long chain of carbon isotopes up to drip lines. The calculated potential-energy curve shows that the first state of the 11Be nucleus has a very large prolate deformation. Such a large deformation can result in a good agreement between the calculated and experimental density distribution of the nucleus. The first state in 13C is also calculated to have a large deformation, and the state in 9He could be a spherical halo attached to a deformed core. The possible halo structure of the neutron orbit in the N=7 isotones is discussed.