Structural properties of amorphous GeSe₂.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Understanding the structure of amorphous chalcogenides like germanium diselenide (GeSe2) is crucial for their application in optical and electronic devices.
• Previous studies have explored GeSe2, but detailed atomic-level structural characterization, especially under ambient conditions, remains an active area of research.

Purpose of the Study:

• To investigate the structural properties of amorphous GeSe2 at 300 K using first-principles molecular dynamics.
• To compare simulation results with experimental neutron diffraction data for validation.
• To elucidate the local atomic arrangements, bonding characteristics, and network topology of amorphous GeSe2.

Main Methods:

• Employed first-principles molecular dynamics (MD) simulations based on density functional theory (DFT).
• Generated amorphous GeSe2 configurations by cooling from a liquid state and performing extensive relaxation at 300 K (22 ps).
• Analyzed structural properties including pair correlation functions and partial structure factors.

Main Results:

• Achieved highly satisfactory agreement between simulated and experimental neutron diffraction data, particularly for Ge-Se and Se-Se correlations.
• Observed predominant formation of GeSe4 tetrahedra, consistent with experimental findings.
• Identified non-negligible proportions of other Ge and Se coordinations, along with homopolar Se-Se bonds and limited Ge-Ge bonds.

Conclusions:

• First-principles MD simulations provide a reliable method for studying amorphous GeSe2 structure.
• The simulated structure, dominated by GeSe4 tetrahedra and edge-sharing connections, closely matches experimental observations.
• The presence of homopolar bonds and varied coordinations offers insights into the network's flexibility and properties.