Ceramics-Silikáty 53 (2) 137-140 (2009)

Elastic properties of soda-lime silica glass from first principles

J. Machacek, O. Gedeon, M. Liska

This work describes preparation of soda-lime-silica (NCS) window glass by the first principles molecular dynamics and calculation of elastic properties from the Hellman-Feynman stresses. Small atomic glassy systems reveal deviations from isotropic solid. Such deviations can be quantified using differences among some stress tensor components. The first principles model applied in this work (DFT: PBE/PAW) underestimates elastic constants by 10-20 %. Size effects were studied with help of the classical molecular dynamics of binary glass Na₂O·3SiO₂ which is close to NCS glass stoichiometry. It was found that elastic properties of small atomic systems are essentially size-independent even if silicate ring statistics reveals strong dependence on the number of atoms.

Keywords: Ab initio molecular dynamics, Soda-lime-silica glass, Structure, Elastic constants, Size effects, Silicate rings