Iom motion in SiO2 melt

Dynamical properties of ions are studied in SiO2 melt by using the molecular dynamics method. The diffusion constant, ionic conductivity and velocity autocorrelation function are calculated at various pressures and temperatures. It is found that the simulated ionic conductivities are close to experimental values, and show an increase with temperature. Diffusion constants become maximum around 10 GPa, in close relation with a marked shift in the coordination number of the Si ion. The velocity autocorrelation function and its spectra are calculated by using the memory function method. These compare well with the molecular dynamics results. Discussion is given on the pressure dependence of dynamical quantities.