Thermodynamically accessible titanium clusters Ti_N, N = 2-32.

Area of Science:

• Materials Science
• Computational Chemistry
• Condensed Matter Physics

Background:

• Understanding the atomic structure and growth mechanisms of small clusters is crucial for designing novel materials with tailored properties.
• Titanium nitride (TiN) clusters are of interest due to their potential applications in catalysis, coatings, and electronics.

Purpose of the Study:

• To investigate the structural properties and growth mechanisms of small titanium nitride (TiN) clusters (N = 2-32).
• To identify key structural motifs and nucleation centers that govern cluster formation and morphology.

Main Methods:

• Employed a genetic algorithm search to explore the potential energy surface (PES) of TiN clusters.
• Utilized density functional theory (DFT) calculations with PBEsol and PBEsol0 functionals for accurate structural refinement and energy evaluation.
• Analyzed cluster structures, growth patterns, and surface areas.

Main Results:

• Identified low-energy TiN cluster structures characterized by interpenetrating icosahedra, icositetrahedra, and Frank-Kasper polyhedra.
• Revealed a growth mechanism driven by the formation of coordination centers composed of these polyhedral units.
• Found that these coordination centers act as nucleation sites, dictating the bulk and morphological features of medium-sized TiN clusters.

Conclusions:

• The growth of TiN clusters follows a hierarchical mechanism involving the assembly of specific polyhedral building blocks around coordination centers.
• The identified coordination centers are critical determinants of TiN cluster structure, stability, and morphology.
• This study provides fundamental insights into the atomic-level formation of TiN clusters, relevant for computational materials design.