It is found that exact and perturbative treatments of the imaginary potential at sub-Coulomb energies in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{12}$C provide close agreement in calculations of both the real and imaginary phase shifts at energies away from resonance.

• Received 20 April 1988

DOI:https://doi.org/10.1103/PhysRevC.38.1488