Phenomenological High Precision Neutron-Proton Delta-Shell Potential
  We provide a successful fit for proton-neutron scattering below pion production threshold up to LAB energies of 350 MeV. We use seven high-quality fits based on potentials with different forms as a measure of the systematic uncertainty. We represent the interaction as a sum of delta-shells in configuration space below the 3fm and a charge dependent one pion exchange potential above 3fm together with magnetic and vacuum polarization effects. Special attention is paid to estimate the errors of the phenomenological interaction. 
R. Navarro Perez, J. E. Amaro, E. Ruiz Arriola
nucl-th