Lagrange-mesh calculations of halo nuclei

In the Lagrange-mesh technique, a variational calculation takes the form of a mesh calculation with the help of the Gauss-Laguerre quadrature, without losing its accuracy. A simplified and improved version of the method is applied to calculations of different properties of three-body systems involving a point cluster and two neutrons, with effective cluster-neutron and neutron-neutron forces. The technique leads to a standard diagonalization of large but sparse matrices. Wave functions are available in analytical form. The He-6, Li-11 and Be-14 halo nuclei are studied and discussed. Matter radii agree with experiment when the binding energies are correctly reproduced with a renormalization of the core-neutron interactions. For Li-11, the need for a low-lying virtual state in this interaction is confirmed. The origin of the binding is analyzed by looking at the different contributions to the energy and at components of the wave function. Asymptotic normalizations, form factors and densities are also determined. (C) 1997 Elsevier Science B.V.