REFLECTION-FREE COMPLEX ABSORBING POTENTIALS

The reflection properties of complex absorbing potentials (CAPs) are examined. Completely reflection-free CAPs are constructed by the introduction of small additional potential terms that remove the residual reflections. In order to simplify the computation of these additional terms several approximations are presented and discussed leading to reflection-reduced CAPs (RCAPs). As an alternative approach a transformative CAP (TCAP) method is introduced that uses a modified kinetic energy operator. By the TCAP method reflections can be avoided even more efficiently. The different effects that are responsible for the reflections are discussed in detail. Similarities and differences to the method of complex scaling are discussed. The feasibility and superiority of the methods to usual CAP methods is demonstrated by calculations of resonance energies for a model potential.