Replacement collision and focuson sequences revisited by full molecular dynamics and its binary collision approximation

Abstract

In displacement cascades, a fraction (roughly one third) of the primary knock-on atom energy is partitioned between two types of linear events: focusons and replacement sequences. While replacement sequences lead to the formation of Frenkel pairs, focusons dissipate energy without creating any damage. The influence of the interatomic potentials on these events is investigated using the binary collision approximation carefully adjusted on molecular dynamics. It was found that the relative amount of energy dissipated by replacement collision sequences (RCS) or by focuson sequences (FS) depends on the potential employed. More specifically, the shorter the potential range, the larger the energy dissipated by RCS at the expense of energy dissipated by FS. Thus the shorter the potential range, the more energy is dissipated by RCS (rather than by FS) and, as a consequence, the more Frenkel pairs formed.