Are zinc clusters really amorphous? A detailed protocol for locating global minimum structures of clusters

Area of Science:

• Physical Chemistry
• Materials Science
• Computational Chemistry

Background:

• Determining the precise structures of free-standing metal clusters is crucial for understanding their properties.
• Previous studies suggested zinc clusters might be amorphous, lacking defined structural characteristics.

Purpose of the Study:

• To accurately assess the structures of free-standing zinc clusters (up to 73 atoms) using a combined experimental and theoretical approach.
• To develop and validate a novel, efficient protocol for locating global minimum cluster structures.

Main Methods:

• Utilized photoemission and mass spectrometry for experimental characterization of zinc cluster anions and cations.
• Employed a hybrid empirical potential-density functional theory (EP-DFT) approach combining Gupta potential sampling with unbiased basin hopping.
• Introduced a new method for optimizing empirical potential parameters for enhanced accuracy.

Main Results:

• The developed EP-DFT methodology accurately reproduces experimental data, indicating reliable prediction of global minimum structures.
• Zinc clusters, contrary to prior claims, exhibit high-symmetry structures across various sizes.
• Identified exotic and unprecedented structural and electronic properties in zinc clusters.

Conclusions:

• The novel EP-DFT protocol is highly effective for determining accurate cluster structures.
• Zinc clusters possess unique characteristics not typically observed in metallic elements.
• This work provides definitive evidence against amorphous structures in zinc clusters, highlighting their ordered nature.