Resonances in external fields without bound predecessors - art. no. 023409

For some potentials, such as the Hulthen and Yukawa potentials, the number of possible bound states depend on an internal potential parameter. Even if the parameters are chosen Such that no bound state exists, resonances occu r after coupling these systems to the continuum, e.g., by an additional ext ernal electric field. We will discuss those resonances which have no bound predecessor. The computations are based on complex coordinate rotations and finite elements.