title: Nature of atomic bonding and atomic structure in the phase-change Ge2Sb2Te5 glass.
abstract: Using electronic structure calculations, we demonstrate a global valence alternation in the amorphous Ge2Sb2Te5, a prototype phase-change alloy for data storage. The resulting p bonding profoundly influences the local atomic structure, leading to right-angle components similar to those in the crystalline counterpart of this chalcogenide glass. The dominance of p bonding is revealed by (i) distributions of the coordination number (CN) and the bond angle, for truly bonded atoms determined based on the electron localization function, and (ii) a direct evaluation of the p (and s) orbital occupation probability for the CN=3 Ge atoms that form 90 degree bonds with neighbors.
authors.affiliation: Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA. mx@jhu.edu
authors.forename: M
authors.initials: M
authors.lastname: Xu
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Cheng
authors.forename: H W
authors.initials: HW
authors.lastname: Sheng
authors.forename: E
authors.initials: E
authors.lastname: Ma