  Linear response theories in the continuum capable of describing continuum
spectra and dynamical correlations are presented. Our formulation is
essentially the same as the continuum random-phase approximation (RPA) but
suitable for uniform grid representation in the three-dimensional (3D)
Cartesian coordinate assuming no spatial symmetry. Effects of the continuum are
taken into account either by solving equations iteratively with a retarded
Green's function or by an absorbing boundary condition. The methods are applied
to giant resonances in a deformed nucleus 12C.

Nuclear Theory