Mass parameters for a dinuclear system

A microscopical method is proposed to derive the diagonal and nondiagonal components of the inertia tensor for a dinuclear system formed in the heavy-ion collision at low energy. The coupling between different modes of motion for the various mass asymmetries and fragment separations is analyzed. The definition of a neck parameter for a dinuclear system is proposed. It is shown that the coupling of the radial and mass-asymmetry modes is weak for almost symmetric configuration but it enhances significantly as the asymmetry increases.