Ab initio molecular dynamics simulations of threshold displacement energies in SrTiO_3

摘要

Ab initio molecular dynamics simulations have been carried out to study low energy recoil events in SrTiO_3. The threshold displacement energies are shown to be strongly dependent on both the orientation and the corresponding atomic arrangement. The minimum threshold displacement energies are 13 eV for an O recoil along the 100 O-O chain, 25 eV for a Sr recoil along the 100 Sr-Sr chain and 38 eV for a Ti recoil along the 110 Ti-Ti chain. The weighted average threshold displacement energies along the primary crystallographic directions are 35.7, 53.5 and >64.9 eV for O, Sr and Ti, respectively. The interstitial configurations produced by the recoil events are 100 and 111 split interstitials for O and Sr, respectively, together with a Ti interstitial occupying a distorted bridge position between two Sr sites. It is found that the recoil events in SrTiO_3 are partial-charge transfer assisted processes, and the partial-charge transfer plays an important role in these recoil events.