The ground-state properties and the soft dipole mode of the 6He nucleus are investigated by the coupled-rearrangement-channel variational method based on an α + n + n cluster model, where the effect of the Pauli principle between the α core and valence neutrons is taken into account. A reasonable binding energy is obtained for the ground state with the use of realistic nn and nα interactions. The resulting ground-state wave function has a long-range tail in the neutron distribution, clearly indicating the neutron halo structure in the 6He nucleus. The calculated distribution of the electric-dipole transition to the 1− excited states shows a localization of the strength to a rather broad peak around Ex ≃ 2.5 MeV with a width of about 4 MeV.
Vol.A575, pp93-117
