Atomic correlations and intermediate-range order in molten and amorphousGeSe2

Abstract

Interatomic potentials consisting of two-body and three-body covalent forces are proposed for ${\mathrm{GeSe}}_2$. Using these in molecular-dynamics simulations, the nature of intermediate-range order is investigated. All the features in S(q), including the first sharp diffraction peak (FSDP), are in agreement with experiments. The FSDP arises from Ge-Ge and Ge-Se correlations between 4–8 Å, and the anomalous decrease in its height on cooling is due to frustration enhanced by increased density. The statistics of edge-sharing tetrahedra and rings are also discussed.