Fredholm Method. I. A Numerical Procedure for Elastic Scattering

The Fredholm expansion of the determinant whose phase gives the elastic-scattering phase shift is "summed" by use of numerical quadrature, reducing the calculation of the phase shift to evaluation of a single finite-dimensional determinant. The method is essentially exact and is applicable, without modification, to nonlocal potentials. Results for the low-energy static and static-exchange scattering of electrons from hydrogen atoms are presented as a simple illustration of the method.