Structural properties of liquid Ge₂Se₃

Sébastien Le Roux, Anita Zeidler, Philip S Salmon, Mauro Boero, Matthieu Micoulaut, Carlo Massobrio

OAI: oai:purehost.bath.ac.uk:publications/514d095e-9567-4fb2-be23-0aa08bb30d02 • DOI: https://doi.org/10.1103/PhysRevB.84.134203

The structural properties of liquid Ge2Se3 were investigated by first-principles molecular dynamics using the Becke-Lee-Yang-Parr scheme for the treatment of the exchange-correlation functional in density functional theory. Our data for the total neutron structure factor and the total pair-distribution function are in excellent agreement with the experimental results. The structure is made predominantly (∼61%) from units comprising fourfold coordinated Ge atoms in the form of Ge-GeSe3 or Ge-Se4 motifs, but there is also a large variety of motifs in which Ge and Se are not fourfold and twofold coordinated, respectively. The miscoordinated atoms and homopolar bonds lead to a highly perturbed tetrahedral network, as reflected by diffusion coefficients that are larger than in the case of liquid GeSe2. The network does, nevertheless, exhibit intermediate range order which is associated with the Ge-Ge correlations and which manifests itself by a first sharp diffraction peak in the total neutron structure factor. The evolution of the properties of GexSe1−x liquids (0 ≤x≤ 1) with composition is discussed.