Loosely bound three-body nuclear systems in the J-matrix approach

We discuss the extension of the oscillator-basis J-matrix formalism on the case of true A-body scattering. The formalism is applied to loosely bound Li-11 and He-6 nuclei within three-body cluster models Li-9 + n + n and a + n + n. The J-matrix formalism is used not only for the calculation of the three-body continuum spectrum wave functions but also for the calculation of the S-matrix poles associated with the Li-11 and He-6 ground states to improve the description of the binding energies and ground state properties. The effect of the phase equivalent transformation of the n-alpha interaction on the properties of the He-6 nucleus is examined. (C) 2004 Elsevier Inc. All rights reserved.