Effective non-Hermitian Hamiltonian and continuum shell model

The intrinsic dynamics of a system with open decay channels is described by an effective non-Hermitian Hamiltonian which at the same time allows one to find the external dynamics, - reaction cross sections. We discuss ways of incorporating this approach into the shell model context. Several examples of increasing complexity, from schematic models to realistic nuclear calculations (chain of oxygen isotopes), are presented. The approach is capable of describing a multitude of phenomena in a unified way combining physics of structure and reactions. Self-consistency of calculations and threshold energy dependence of the coupling to the continuum are crucial for the description of loosely bound states.