We carefully compare the one-dimensional Wentzel, Kramers, Brillouin barrier tunneling model, and the one-channel Schrödinger equation with a complex optical potential calculation of heavy-ion fusion, for a light and a heavy system. It is found that the major difference between the two approaches occurs around the critical energy, above which the effective potential for the grazing angular momentum ceases to exhibit a pocket. The value of this critical energy is shown to be strongly dependent on the nuclear potential at short distances, on the inner region of the Coulomb barrier, and this dependence is much more important for heavy systems. Therefore the nuclear fusion process is expected to provide information on the nuclear potential in this region. We compare calculations with available data to show that the results are consistent with this expectation.

• Received 18 May 2018
• Revised 6 August 2018

DOI:https://doi.org/10.1103/PhysRevC.98.044617