A statistical approach based on the Weisskopf evaporation theory has been developed to describe the deexcitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating γ-rays, light particles（neutrons, protons, α etc） in competition with binary fission,in which the structure effects（shell correction, fission barrier, particle separation energy） contribute to the processes.The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies.The available data of fusion-evaporation excitation functions in the ^28Si＋^198Pt reaction can be reproduced nicely within the approach.
The role of positive Q-value neutron transfers in sub-barrier fusion reactions has been studied with a modified quantum coupled channels model with all order couplings（CCFULL model）. Neutron rearrangement related only to the dynamical matching condition with no free parameters is implemented in the model, which provides a way to understand especially the Q-value dependence of sub-barrier fusion reactions. The fusion cross sections of the collision systems 40^Ca＋94,96^Zr have been calculated and analyzed. The general trend of experimental data can be reproduced well with additional channels for neutron rearrangement. We find that enhancement of sub-barrier fusion cross sections is closely related to the Q-value of the transferred neutrons, in particular for channels with sequential even number transferred neutrons.
