Method for Lippmann-Schwinger equations

A recently proposed degenerate-kernel scheme for solving Fredholm integral equations of the second kind is extended to singular equations of the Lippmann-Schwinger type. Numerical calculations of on- and off-shell t-matrix elements are carried out at positive and negative energies, for the 1S0 Reid soft-core nucleon-nucleon potential. Satisfactory convergence is achieved, even with the simplest version of the s