Non-Hermitian effective Hamiltonian and continuum shell model

The intrinsic dynamics of a system with open decay channels is described by a non-Hermitian effective 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. The approach is capable of describing a multitude of phenomena in a unified way combining physics of structure and reactions. Self-consistency of calculations for a chain of nuclides and threshold energy dependence of the continuum coupling are crucial for the description of loosely bound states. Schematic and realistic examples of open many-body systems where internal configuration mixing is generated by pairing are presented.