SIMULATION OF VACANCIES IN A GLASS BY MOLECULAR-DYNAMICS

We performed a molecular-dynamics simulation of amorphous argon with a Lennard-Jones potential. By studying the behaviour of a vacancy, created by turning off the potential of a selected atom, over a wide range of sites, three different behaviours were distinguished: an on-site dissipation of the vacancy by a rearrangement of the nearest neighbours, a reconstitution of the initial site by atomic jumps, with the vacancy dissipation along the path of the jumps, and stability in which nothing happens. At 0.2 K, the vacancy is stable on more than half of the sites of introduction. An increasing stability of the vacancy, as well as an increasing probability for annihilation by dissipation, was correlated with increasing hydrostatic pressure. An increasing proportion of decays by reconstitution could be correlated with the conjunction of both lower pressure and lower sphericity.