Exploring the role of low-lying intrinsic degrees of freedom and their impact on fusion cross-sections

This work focuses on examining the low-lying intrinsic degrees of freedom and their impact on fusion dynamics. Fusion cross-sections were calculated using the coupled-channel code CCFULL for four specific reactions: [Formula: see text]Ge, [Formula: see text]Nd, [Formula: see text]W, and [Formula: see text]W, all conducted at energies below the Coulomb barrier across various energy levels. Vibrational and rotational features were studied concerning energy to distinguish their respective effects on fusion properties. The results indicate that the theoretical calculations for the nuclei [Formula: see text]Ge, [Formula: see text]Nd, [Formula: see text]W and [Formula: see text]W closely match the experimental data, particularly for the [Formula: see text] excited states. While slight discrepancies are observed for other excited states ([Formula: see text] and [Formula: see text]), overall agreement remains significant. Additionally, the study reveals that hexadecapole deformation with different magnitudes have significant influences on the fusion cross-section. In cases where [Formula: see text] has a positive value, rotational levels beyond [Formula: see text] have minimal impact on the cross-section, resulting in a notable difference in the contribution of sequential channels. In contrast, for negative [Formula: see text] values, rotational energy levels up to the [Formula: see text] state substantially affect the fusion characteristics. Furthermore, the analysis extends to the estimation of the relative change ([Formula: see text]) between the excited states and the ground state, both with and without considering coupling terms.