THE STRUCTURE AND DYNAMICS OF SODIUM DISILICATE GLASS BY MOLECULAR-DYNAMICS SIMULATION

The method of molecular dynamics simulation has been used to study the structural and dynamical properties of sodium disilicate glass Na2Si2O5. Realistic empirical potentials have been employed, including three-body terms. The simulated glass has a structure which agrees well with experimental diffraction data. It contains evidence for the microsegregation of alkalis and non-bridging oxygens, supporting the predictions of the modified random network model. Protracted calculations at different temperatures over the range 1000-2000 K reveal the mobility of sodiums compared with the rigidity of silicons and oxygens in the simulated glass. The diffusion activation energy lies remarkably close to the experimental value.