Molecular dynamics investigations of glassforming binary Lennard-Jones systems with different anharmonicities

Dynamical properties of three glassforming binary Lennard-Jones systems with different anharmonicities of the interaction potential have been studied by molecular dynamics simulations. The onset temperature of slow dynamics TA, the Mode Coupling theory critical temperature TC and the Vogel–Fulcher–Tamman temperature TVFT have been determined for the three models. A good agreement is found with most of the predictions of the Mode Coupling Theory. However, a detailed analysis of the master curve obtained from the superposition of the intermediate scattering functions reveals a significative temperature dependence of the stretched exponent β over a wide temperature range from the liquid state to the glass transition. It is shown that both fragility and stretched exponent β unambigously correlate with anharmonicity of the interaction potential.