An analytical expression for the calculation of the nucleus-nucleus potential has been derived from an empirical formula which describes the fusion excitation function. The nucleus-nucleus potentials calculated for the projectiles ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ in the interaction region ∼3–6.5 fm by the above procedure agree remarkably well with the real part of the respective optical potentials determined from the analysis of elastic scattering data which exhibit the ‘‘rainbow’’ phenomenon.

• Received 20 September 1985

DOI:https://doi.org/10.1103/PhysRevC.34.357