Properties of microscopic nucleus-nucleus interaction for molecular resonance formation in12C+12Cand3α+3αsystems

Abstract

Properties of microscopic interaction potentials between two ${}^{12}\mathrm{C}$ nuclei are discussed in connection with the formation of ${}^{12}{\mathrm{C}+}^{12}\mathrm{C}$ and $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ molecular resonances. The nucleus-nucleus interactions are calculated by the double-folding procedure based on a realistic nucleon-nucleon interaction (DDM3Y) and microscopic ${}^{12}\mathrm{C}$ transition densities calculated from 3\ensuremath{\alpha}-RGM wave functions. The interaction potential can be written as the sum of the monopole part obtained from the monopole density and the multiple parts generated from the quadrupole component of the density. We discuss the role of the monopole and multipole parts of the potential separately. It is shown that the multipole part is very strong in the channels with $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ structure and the energy positions of the $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ molecular bands generated by the monopole potential are largely modified. The effect is moderate but non-negligible on the molecular bands with the ${}^{12}{\mathrm{C}+}^{12}\mathrm{C}$ dinuclearlike structure and largely modifies the band crossing diagram between the elastic and aligned-inelastic molecular bands. The channel coupling effect among the ${}^{12}{\mathrm{C}+}^{12}\mathrm{C}$ channels, namely, the elastic channel and the single- and mutual-${2}_{1}^{+}$ excitation channels is also investigated. Due to the strong coupling between the ground and ${2}_{1}^{+}$ states of ${}^{12}\mathrm{C},$ the resonance wave functions obtained by the coupled-channel calculation have an additional radial node compared with those of the single-channel resonances. All the results are discussed in connection with the band crossing model which was believed to be successful in describing the ${}^{12}{\mathrm{C}+}^{12}\mathrm{C}$ molecular resonances.