An analytical expression to evaluate the dispersive contribution to the rea
l potential for complicated energy and radial shape dependences of the empi
rical imaginary part is presented and applied to O-16-O-16 at intermediate
energies. The calculated dispersive potentials describe the general feature
s of the measured angular distributions and the energy dependence of the vo
lume integrals. The best agreement with the elastic scattering data is obta
ined when the imaginary part is simplified to consist only of a volume term
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