Structural Evolution and Stability Trend of Small-Sized Gold Clusters Au (n = 20-30)

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Understanding the structural evolution and stability of pure metal clusters is crucial for their application in catalysis and nanotechnology.
• Gold clusters (Au_n) exhibit unique properties that are highly dependent on their size and geometric structure.

Purpose of the Study:

• To investigate the structural evolution and stability patterns of neutral gold clusters (Au_n) in the size range of n = 20-30.
• To identify new ground-state structures and confirm existing ones for these gold clusters.
• To evaluate computational methods for studying gold cluster properties.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to determine equilibrium geometries and stability.
• Systematic examination of cluster structures for sizes n = 20 to 30.
• Calculation of energy gaps, excitation energies, and exciton binding energies.

Main Results:

• New ground-state structures were identified for gold clusters Au₂₁-Au₃₀.
• Stable configurations for Au₂₁-Au₂₃ are derived from the pyramidal Au₂₀ structure.
• Flat-cage structures are favored for Au₂₄ and Au₂₅, while pyramidal motifs dominate larger clusters (n=26-30).

Conclusions:

• The study provides a detailed understanding of structural transitions in small to medium-sized gold clusters.
• Pyramidal motifs are found to be prevalent in larger gold clusters (n=26-30), differing from prior reports of tubular structures.
• A density functional with long-range exchange effects is recommended for accurate investigations of both ground and excited states of gold clusters.