Topological analysis on structural transition under compression and structural heterogeneity in silica glass: a molecular dynamics simulation

ABSTRACT

We perform a simulation of the structural transition and structural heterogeneity (SH) in silica glass at 500 K, in the range 0–100 GPa. Topological analysis is performed based on the basic units and transition of O_xx and O_xy atoms (x, y = 4, 5, 6). The result indicates that the structure of silica glass comprises D4, D5 or D6 domain, depending on pressure. In the range 5–20 GPa, silica glass occurs structural transformation from D4 to D6 domain. Upon compression, structural transition is accompanied with the O_xx→O_xy transition which includes two parallel processes: merging and splitting of domains which relate to the change of BD atoms. The SH is considered by means of the link-cluster function. We found that at pressure below 5 and beyond 20 GPa, SiO_x units are non-uniformly distributed in the space. In contrast, they are uniformly distributed in the range 5–20 GPa.

KEYWORDS:

• Silica glass
• structural transition
• structure heterogeneity
• domain
• link-cluster function

Acknowledgment

This research is funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 103.02-2018.312.

Disclosure statement

No potential conflict of interest was reported by the author(s).