J. Kieffer, HIGH-FREQUENCY STRUCTURAL RELAXATION IN SODIUM SILICATES - A MOLECULAR DYNAMIC STUDY, Journal of non-crystalline solids, 172, 1994, pp. 1285-1291
The dynamic behavior of sodium silicate liquid and glassy structures w
ere investigated by means of molecular dynamic simulations. Particle i
nteractions were modeled using the central force Born-Mayer potential.
Simulations were carried out over approximately half a nanosecond. Dy
namic susceptibility spectra describing the response of the alkali cat
ions to thermal activation are reported for various temperatures. The
diffusion of alkali cations was found to be solid-like, i.e., occurrin
g as sudden jumps separated by long waiting periods, even above the gl
ass transition temperature. The intermediate scattering functions appr
oximately follow a stretched exponential behaviour, with a stretching
exponent of 0.8. The characteristic relaxation times for cation motion
depend on the probing wave vector according to a power law, with an e
xponent close to -2.