Iom motion in SiO2 melt

Dynamical properties of ions are studied in SiO2 melt by using the molecula r dynamics method. The diffusion constant, ionic conductivity and velocity autocorrelation function are calculated at various pressures and temperatur es. It is found that the simulated ionic conductivities are close to experi mental values, and show an increase with temperature. Diffusion constants b ecome maximum around 10 GPa, in close relation with a marked shift in the c oordination number of the Si ion. The velocity autocorrelation function and its spectra are calculated by using the memory function method. These comp are well with the molecular dynamics results. Discussion is given on the pr essure dependence of dynamical quantities.