Semimicroscopic modeling of heavy-ion fusion reactions with multireference covariant density functional theory

We describe low-lying collective excitations of atomic nuclei with the multireference covariant density functional theory and combine them with coupled-channels calculations for heavy-ion fusion reactions at energies around the Coulomb barrier. To this end, we use the calculated transition strengths among several collective states as inputs to the coupled-channels calculations. This approach provides a natural way to describe anharmonic multiphonon excitations, as well as a deviation of rotational excitations from a simple rigid rotor. We apply this method to subbarrier fusion reactions of Ni58+Ni58,Ni58+Ni60, and Ca40+Ni58 systems. We find that the effect of anharmonicity tends to smear the fusion barrier distributions, better reproducing the experimental data compared to the calculations in the harmonic oscillator limit.