We study the heavy-ion reaction at sub-barrier energies for <sup>16</sup>O+<sup>144,154</sup>Smsystems using full order coupled-channels formalism. We especially investigate the effect of fusion and quasi- elastic barrier distributions on the surface diffuseness and the coupling radius parameters of the nuclear potential for these systems. We found that the structure of fusion and quasi-elastic barrier distributions is more sensitive to the surface diffuseness and coupling radius parameters for the reaction with spherical target, <sup>16</sup>O+<sup>144</sup>Sm systemcompared to the reaction that involves the deformed target, i.e., <sup>16</sup>O+<sup>154</sup>Sm system. In more detail, the results of coupled-channels calculations for the fusion and the quasi-elastic barrier distributions for deformed target are not sensitive to the choice of the coupling radius and surface diffuseness parameters. In mark contrast, the structure of the fusion and the quasi-elastic barrier distributions for spherical target are very sensitive to the coupling radius and surface diffuseness parameters. We found that the small surface diffuseness parameter smeared out the fusion barrier distributions and the larger coupling radius smoothed the high energy peak of the quasi-elastic barrier distributions. We also found that the larger coupling radius, , is required by the experimental quasi-elastic barrier distribution for the <sup>16</sup>O+<sup>144</sup>Sm system whereas the experimental fusion barrier distribution compulsory the small value, i.e., .
Role of noncollective excitations in heavy-ion fusion reactions and quasi-elastic scattering around the Coulomb barrier
