Nano-scaled dynamics of iodine-tetrahedron in α-AgI

A molecular dynamics method is applied to study the dynamical correlation between diffusing cations and tetrahedron (THs) of the anion bcc sublattice in a superionic conductor (SIC) α-AgI. Geometric quantities such as volume and area of a TH are calculated as a function of a distance between a mobile Ag ion and a TH. When a silver ion is approaching to the boundary surface of an empty marked tetrahedron, in which a silver ion is not included, the area of a boundary plane of the TH becomes larger in order that the silver ion may be easy to enter the TH. Tetrahedrons composed by four iodine ions repeat contraction and expansion correlating with motion of mobile silver ions.