A parameter-free optical potential for the heavy-ion elastic scattering   proces
  Thirty elastic scattering angular distributions for seven heavy-ion systems, in wide energy ranges, have been studied with the aim of systematizing the optical potential, real and imaginary parts, in a global way. The framework is: i) an extensive systematization of nuclear densities, ii) the energy dependence of the bare potential accounted by a model based on the nonlocal nature of the interaction, and iii) the real and imaginary parts of the optical potential assumed to have the same radial shape. 
M. A. G. Alvarez, L. C. Chamon, M. S. Hussein, D. Pereira, L. R.   Gasques, E. S. Rossi Jr., C. P. Silva