In the low energy atomic collision of ε ≤ 0.1, the energy dissipation of projectile ion is mainly by the nuclear stopping. In this energy rangeZ-oscillation appears on ranges and range stragglings. In order to explain this osciallation from the viewpoint of molecular effect on interatomic potentials, an extended Hückel method is adopted for potential calculation. TheZ-dependence on interatomic potentials to describe respective atomic collisions is similar to that ofZ1-range oscillation. It suggests a possibility of molecular effect on theZ1-range oscillation.