Quarks and Neutron Halo Nuclei, Nuclear Clusters and Nuclear Molecules

It is shown that the hole in the centre of $^{3}H$, $^{3}He$ and $^{4}He$, the neutron halos in nuclei, the $\alpha -$ and other clustering effects in nuclei and the nuclear molecules all basically arise due to the same underlying effect. We shall show that all these ground state properties of nuclei are manifestations of quark effects. The role of triton clustering in very neutron rich nuclei is emphasized. All these require the concept of hidden colour states which arise from confinement ideas of QCD for the multi-quark systems. This provides comprehensive understanding of diverse nuclear effects and makes unique predictions.