''Optimal'' approximation and the realistic nucleon-nucleon interactions

The ''optimal'' approximation in the presence of the realistic nucleon-nucleon forces is tested for the proton-deuteron elastic scattering in the laboratory kinetic energy range between 100 and 450 MeV. The particular emphasis is put on the large scattering angles where the corrections to the pd scattering amplitude are governed by the energy derivative of the off-shell nucleon-nucleon amplitudes. At 1800 the second-order relative corrections amount to 10 or 20 % in the energy range up to 320 MeV and are much larger at higher energies, especially at about 400 MeV: the energy corresponding to the zero of the scalar deuteron form factor. In the forward direction the corrections are very small: 1 to 5 %. Their maximum values are found for the proton-bound neutron scattering at the intermediate angles close to 900