Spatially heterogeneous dynamics and dynamic facilitation in a model of   viscous silica
  Performing molecular dynamics simulations, we find that the structural relaxation dynamics of viscous silica, the prototype of a strong glass former, are spatially heterogeneous and cannot be understood as a statistical bond breaking process. Further, we show that high particle mobility predominantly propagates continuously through the melt, supporting the concept of dynamic facilitation emphasized in recent theoretical work. 
Michael Vogel and Sharon C. Glotzer