A study of the binding mechanism of 11Li by the 9Li+n+n model

The binding mechanism of Li-11 is investigated on the basis of the Li-9+n+n three-cluster model. To understand the weakly-bound structure creating the neutron-halo structure, we solve the Li-9+n+n three-cluster motion using the reliable Li-9-n interaction constructed on the basis of the recent experimental data for Li-10 of Bohlen et al. The neutron-neutron correlation is carefully investigated by employing the extended basis functions described by the hybrid-VT model. The result for the binding energy exhibits considerable improvement but is still small in comparison with experiments. To address this shortcoming, an additional correlation accompanied by the pairing excitation of the Li-9-core is discussed.