Structural properties of amorphous GeSe2.

By using first-principles molecular dynamics within density functional theory, we study the structural properties of amorphous GeSe2 at T = 300 K. The amorphous configurations have been obtained via cooling from the liquid state followed by extensive relaxation (22 ps) at T = 300 K. The agreement with neutron diffraction experiments is very satisfactory, in particular for the pair correlation functions in real space and the partial structure factors in reciprocal space describing the Ge-Se and the Se-Se correlations. Some residual differences between theory and experiment are found for Ge-Ge correlations. The network organizes itself through the predominant presence of GeSe4 tetrahedra. However, other coordinations exist in non-negligible proportions for both Ge and Se. Homopolar bonds are found for Se, and, in a very limited extent, also for Ge. The number of edge-sharing connections reproduces the experimental data.