Diffusion mechanisms in lithium disilicate melt by molecular dynamics simulation

In this work we study the diffusion mechanisms in lithium disilicate melt using molecular dynamics simulation, which has an edge over other simulation methods because it can track down actual atomic rearrangements in materials once a realistic interaction potential is applied. Our simulation results of diffusion coefficients show an excellent agreement with experiments. Using the diffusion coefficient of silicon, we are able to demonstrate that this glass-forming liquid obeys the well-known Stokes-Einstein relation at least down to 1600 K. The relaxation obtained via the self-part of the intermediate scattering function decouples from viscosity measurements at temperatures below 2000 K. Additionally, an analysis on the dynamical behavior of slow-diffusing atoms reveals explicitly the presence of dynamical heterogeneities.