Molecular Dynamics Study of Ag₃SI

Superionic conductor Ag 3 SI is simulated by the molecular dynamics with a simple ionic potential for both α and β phases. The simulated result show that Ag ions stay near 6(b) sites of the anion bcc lattice in β phase, while they diffuse preferentially occupying 12(d) sites of the bcc lattice in α phase. The calculated Debye-Waller factor of the anions and the self-diffusion constant of Ag ions are in good agreement with the experiments. The velocity autocorrelation functions, the current-current correlation function and their frequency spectra are also obtained. The calculated moment ratio of the displacement suggests that the migration mechanism of Ag ions in α phase is a discrete hopping rather than a continuous motion.