Structure and dynamical heterogeneity in GeO

We used molecular dynamics (MD) simulation to clarify the structure and dynamics in GeO2 liquid. MD models consisting of 5499 atoms were constructed in the range of temperature from 2000 K to 4500 K and at ambient pressure. The structure of GeO2 liquid is built mainly by GeO4 basic structural units that are linked to each other through common oxygen atoms to form a tetrahedral network. The dynamic heterogeneity (DH) is investigated by calculating the link-cluster function flc(r, t) and init-bond function fib(t). The link-cluster function for sets of random, mobile and immobile atoms at low temperature is different. This is evidence of DH in GeO2 liquid. Diffusion mechanism in GeO2 liquid is via bond-breaking mechanism that relates to the init-bond function. The bond breaking and new bond forming in GeO2 liquid are realized via exchange of coordinated atoms. The existence of separate fast regions (places of the high mobility atoms) and slow regions (places of the low mobility atoms) is the origin of DH