Calculation of resonances by analytical continuation: role of asymptotic behavior of coupling function
Abstract
The regularized analytical continuation method (RAC) counts among the most powerful modern method for determination of resonance energies and resonance widths of low energy atomic and molecular systems including large systems of biological importance. By this method the resonance state is transformed into bound state by addition of an attractive potential.
In this paper the choice of the perturbation potential is discussed and the performance of the method studied using model potential. It is shown that for correct applications of the RAC method the knowledge of the asymptotic behavior of the basic ingredient of the method, the coupling function lambda(kappa), is important.
In this paper we find the correct asymptotic form of lambda(kappa) for broad class of realistic potentials and for nonzero values of angular momentum. New RAC formula convenient for singular perturbation potentials is proposed.