Figure 3 Impact parameters vs dwell time curves of classically modelled He-Rh(311) three-dimensional scattering (atomic units are used).  and  are the impact parameters in the direction x and y, respectively. (A) Regular curve when. (B) Irregular curve when . Around , a chattering region appears in the curve. (C) and (D) are the same cases as (B), except the curve is zoomed in. Regular and irregular parts of the curves occur.