Two bond-exchange modes in sodium silicate liquids: Slide and oscillation modes

Abstract

The network structure of polymerized silicate liquids suppresses the diffusion mechanism of silicon and oxygen atoms. Several diffusion model for these network forming elements have been presented based on nuclear magnetic resonance spectroscopy and molecular dynamics simulations. The authors' previous study introduced the concept of bond-breaking/forming particle, that can analyze quantitatively the certain bond exchange event from pair correlation functions of those particles. In this study, the angular part of the pair-correlation function of bond-breaking/forming particles was introduced, and an atomistic description of the two different bond exchange modes, that found in the author's previous study, was revealed. The first peak represent exchange of SiO bonds in a sliding manner, whereas the second peak correspond to exchange in an oscillating manner. The inner product of vectors correspond to broken and newly formed bond is zero to positive in former mode, negative in latter mode.