Competition between supercluster and stuffed cage structures in medium-sized Ge(n) (n=30-39) clusters

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Understanding the atomic structure and properties of germanium clusters is crucial for developing novel nanomaterials and electronic devices.
• Previous studies have focused on smaller germanium clusters, leaving a gap in knowledge for medium-sized clusters.

Purpose of the Study:

• To perform an unbiased global search for the lowest-energy structures of germanium clusters (Ge(n)) in the size range of 30 to 39 atoms.
• To investigate the structural motifs and size-dependent properties of these medium-sized germanium clusters.
• To compare theoretical findings with experimental data for validation.

Main Methods:

• Employed a genetic algorithm (GA) combined with a tight-binding (TB) model for an unbiased global structure search.
• Utilized Density Functional Theory (DFT) calculations for geometry optimization of potential isomer structures.
• Analyzed cluster properties including binding energy, Highest Occupied Molecular Orbital-Lowest Unoccupied Molecular Orbital (HOMO-LUMO) gap, and ionization potential.

Main Results:

• Identified preferred supercluster structures for Ge(n) (n=30-39), characterized by stable subunits (e.g., Ge(10), Ge(6)) linked by bridging atoms.
• Observed distinct size-dependent trends in binding energy, HOMO-LUMO gaps, and ionization potentials.
• Found good agreement between calculated properties and available experimental measurements.

Conclusions:

• The study reveals a novel supercluster motif governing the structure of medium-sized germanium clusters.
• The findings provide a deeper understanding of structure-property relationships in Ge(n) clusters.
• This work serves as a valuable reference for future experimental and theoretical investigations in germanium cluster science.