  Fusion can be described by the time evolution of a dinuclear system with two
degrees of freedom, the relative motion and transfer of nucleons. In the
presence of the coupling between two collective modes, we solve the
Fokker-Planck equation in a locally harmonic approximation. The potential of a
dinuclear system has the quasifission barrier and the inner fusion barrier, and
the escape rates can be calculated by the Kramers' model. To estimate the
fusion probability, we calculate the quasifission rate and the fusion rate. We
investigate the coupling effects on the fusion probability and the cross
section of evaporation residue.
