Regular Article

Structure and dynamical heterogeneity in GeO₂ liquid: a new approach

School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Hai Ba Trung District, Hanoi City, Vietnam

^a e-mail: lan.maithi@hust.edu.vn

Received: 14 January 2019
Received in final form: 2 April 2019
Published online: 3 June 2019

Abstract

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 f_lc(r, t) and init-bond function f_ib(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.