Network topology and the fragility of tetrahedral glass-forming liquids

Network-forming liquids comprising tetrahedral motifs are investigated by large-scale molecular dynamics computer simulations within the framework of an ionic interaction model. The network topology is controlled by varying the anion polarizability, which governs the intertetrahedral bond angle, for different system densities. A coupling is found between the growth in magnitude and range of extended range oscillations and the appearance of ordering on an intermediate length scale. The interrelation between the system fragility and the structural arrangements on these two different length scales shows the trends that are observed for glass-forming systems. In particular, the fragility increases with number of edge-sharing motifs.