First-principles structures and stabilities of AlN+ (N = 46-62) clusters

Area of Science:

• Physical Chemistry
• Computational Materials Science
• Cluster Physics

Background:

• Understanding the structure and stability of atomic clusters is crucial for materials science.
• Aluminum cluster ions (Al(N)(+)) exhibit unique properties relevant to catalysis and materials design.
• Recent calorimetric experiments have indicated a melting-like transition in these clusters.

Purpose of the Study:

• To determine the global minimum energy structures for aluminum cluster ions Al(N)(+) where N ranges from 46 to 62.
• To provide a theoretical basis for rationalizing experimental observations of the melting-like transition in Al(N)(+).

Main Methods:

• Utilized pseudopotential density functional theory (DFT) static calculations.
• Employed the spin-polarized generalized gradient approximation (GGA) for electronic structure determination.
• Investigated structural candidates for global minimum energy configurations.

Main Results:

• Identified plausible global minimum structures for Al(N)(+) (N = 46-62).
• Observed that clusters with N >= 48 tend to adopt fragments of the face-centered-cubic (fcc) lattice, albeit with distortions and defects.
• Found that (111)-like surfaces contribute to stabilization, with clusters avoiding high proportions of (100)-like surfaces.
• Noted disordered structures for Al(46)(+) and Al(47)(+).
• Indicated enhanced stability for N = 51, 57, and 61, and a significant structural change between Al(55)(+) and Al(56)(+).

Conclusions:

• The calculated structures provide a theoretical framework for understanding the experimental melting-like transition in Al(N)(+).
• The prevalence of fcc fragments and surface characteristics significantly influences cluster stability.
• The findings correlate qualitatively with experimental observations, paving the way for further investigation.