  A simple pair potential, which equilibrium pair separation can be varied
under a fixed interaction range, has been proposed. The new potential can make
both face-centered-cubic(fcc) and body-centered-cubic(bcc) structure stable by
simply changing one parameter. To investigate the general effect of the
potential shape on cluster structures, the evolution of cluster structures is
calculated for different equilibrium pair separations. The small size
clusters($N<25$), which adopt the polytetrahedra, are almost independent on the
details of the potential. For the large size clusters($25<N<150$), the
potential with large equilibrium pair separation trends to stable decahedra and
close-packed structure, disordered clusters appear for the potential with small
equilibrium pair separation, while for the middle range of equilibrium pair
separation, the icosahedra are dominated.
