Halos in medium-heavy and heavy nuclei with covariant density functional theory in continuum

Covariant density functional theory with a few parameters has been widely used to describe the ground- and excited-state properties for nuclei all over the nuclear chart. In order to describe the exotic properties of unstable nuclei, the contribution of the continuum and its coupling with bound states should be treated properly. In this review, the development of the covariant density functional theory in continuum is introduced, including the relativistic continuum Hartree-Bogoliubov theory, the relativistic Hartree-Fock-Bogoliubov theory in continuum and the deformed relativistic Hartree-Bogoliubov theory in continuum. Then the descriptions and predictions for the neutron halo phenomena in both spherical and deformed nuclei will be reviewed. The diffuseness of the nuclear potentials, nuclear shapes and density distributions, and the impact of the pairing correlations on nuclear size are discussed.National Key Basic Research Program of China [2013CB834400]; Natural Science Foundation of China [10975008, 11175002, 11105005, 11105010, 11035007, 11128510, 11121403, 11120101005, 11211120152, 11235002, 11275248, 11205004, 11335002]; Research Fund for the Doctoral Program of Higher Education [20110001110087]; Chinese Academy of Sciences [KJCX2-EW-N01]SCI(E)REVIEWmengj@pku.edu.cn; sgzhou@itp.ac.cn94