Molecular Dynamics Studies of Superionic Conductors. Interionic Potential and Ion-Conducting Phase

As a simple model for α-AgI, a system with ionic potentials consisting of only a Coulombic and a soft-core repulsive terms is investigated with use of a molecular dynamics method. The system has interesting scaling properties and is characterized by the ratio of the ion core radii and \(\), the ratio of potential strengths between the Coulombic and soft-core terms. It is shown that there exists a range of \(\) in which the iodine sublattice forms a stable bcc structure and silver ions are disordered. The \(\)- and temperature dependences of various quantities are examined. In this range of \(\) the diffusion and the density distribution of silver ions are in accord with the experiments.