Ab initio molecular dynamics simulations of threshold displacement energies in SrTiO3

Ab initio molecular dynamics simulations have been carried out to study low energy recoil events in SrTiO3. 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 SrTiO3 are partial-charge transfer assisted processes, and the partial-charge transfer plays an important role in these recoil events.