SIMULATION OF VACANCIES IN A LENNARD-JONES GLASS

The behaviour has been studied of a vacancy, created by the removal of a selected atom in an amorphous argon-like Lennard-Jones system by means of a molecular dynamics simulation. Three different types of behaviour could be observed: an on-site dissipation of the vacancy by a local rearrangement of the nearest neighbours, a reconstitution of the initial site by atomic jumps, and stability with a large distribution for the final volumes of the vacancies. At a temperature of 0 K, the vacancy is stable on more than half of the sites. An increasing stability of the vacancy, as well as an increasing probability for annihilation by dissipation, was correlated with hydrostatic pressure. An increasing proportion of decays by reconstitution is correlated with the conjunction both of a lower pressure and a lower sphericity.