Microscopic Optical Potential Analysis of Heavy-Ion Fusion: A Review of the Double-Folding Model with M3Y Interaction

Abstract

The microscopic optical model, in which the heavy-ion interaction is built by folding an effective nucleon–nucleon force with the densities of the colliding nuclei, provides a nearly parameter-free description of the fusion barrier and the near-barrier cross section. This article presents the double-folding formalism with the density-dependent M3Y effective interaction and applies it to heavy-ion fusion, taking the O+Pb reaction as the principal benchmark. It is shown that the real folding potential, with a renormalization factor consistent with unity, reproduces the empirical barrier height and radius, and that the explicit density dependence of the interaction, although it strongly modifies the potential in the nuclear interior, leaves the barrier region almost unchanged. Combined with a short-range imaginary potential and solved by partial-wave barrier penetration, the folding model reproduces the measured fusion excitation function above and below the barrier, and accounts for the characteristic energy dependence of the real and imaginary volume integrals known as the threshold anomaly. A survey of systems spanning a wide range of charge products confirms the predictive, microscopic character of the approach.