Atomistic modeling approach to the thermodynamics of sodium silicate glasses

A good description of the vibration modes of silicate glasses is necessary for the accurate determination of their thermodynamical properties. While the properties of amorphous SiO ₂ are well-known, those of more complex silicate glasses remain poorly described. In this work, the atomic-scale models have been used to investigate the vibration modes and thermodynamical properties of amorphous sodium silicate (Na ₂O) _x(SiO ₂) _{1− x}. Several empirical potentials have been considered, and their predictions have been compared to available experimental data. Different Na ₂O concentrations have also been simulated, highlighting the effect of sodium network modifiers on vibration spectra and thermodynamical properties. Statistical effects related to the simulation box size have been investigated, which helps interpreting quantitative results from simulations based on small systems, for example, electronic structure calculations. The potentials used can describe different oxides besides SiO ₂ and Na ₂O. The results presented here pave the way for future use of these potentials to study more complex glasses with different types of network formers and modifiers.