On the Chemical Bonding of Amorphous Sb₂Te₃

An analysis of the electronic structure and chemical bonding in glassy Sb₂Te₃ is carried out by means of density functional theory calculations, on a computer model generated by ab initio molecular dynamics. A significant antibonding character of electronic states below the Fermi level is observed, which is the characteristic feature of phase-change memory materials. Near-linear chains, with alternating long and short bonds, are found to be an important geometric structural pattern related to this antibonding signature. The electronic structure and chemical bonding analysis, herein, reveals an emergent character of hypervalent interactions in the amorphous phase of Sb₂Te₃. The intimate link between these near-linear chains, hypervalent interactions, and the fast-switching properties of this technologically important material provides valuable information for the future development of phase-change memory materials.