Structure of liquid GexSe1-x at the stiffness threshold composition

We investigate by first-principles molecular dynamics the structural properties of liquid GeSe4, i.e., GexSe1-x at x = 0.2. This composition is very close to the so-called stiffness threshold composition, at which dramatic changes in a series of experimental properties occur. The calculated total neutron structure factor is in very good agreement with experiment. The results show that liquid GeSe4 is a good prototype of a chemically ordered network. It consists of GeSe4 tetrahedra that are connected by either shared Se atoms or Se chains.