Structural and transport properties in the Ag3SI system: a molecular dynamics study of alpha, beta and molten phases

Structural properties of the β phase and transport properties of the superionic (α), β and molten phases of Ag3SI are investigated by molecular dynamics simulation (MD), using Vashishta–Rahman (VR)-type potentials. In the β phase, the pair distribution functions are quite different from those in the α phase, because anions form the order arrangement in a bcc structure in the β phase, whereas anions occupy the lattice points randomly in the α phase. The silver distributions obtained in the β phase are in good agreement with experimental results, which are quite different from those in the α phase, as we reported in a previous paper. The conductivities obtained in the α and β phases by MD are also in good agreement with experiments. The frequency dependent diffusion coefficients in the α and β phases, which are derived from the temporal Fourier transformation of the velocity autocorrelation function, have similar features to the neutron TOF spectra data.