Structures and stabilities of (MgO)n nanoclusters

Area of Science:

• Computational Chemistry
• Materials Science
• Solid-State Physics

Background:

• Understanding the structure-property relationships of magnesium oxide (MgO) clusters is crucial for designing new materials.
• Previous studies have explored various cluster sizes, but a comprehensive optimization of global minima for (MgO)n is needed.

Purpose of the Study:

• To determine the lowest energy isomers for (MgO)n clusters using advanced computational methods.
• To investigate the structural evolution and energetic stability of (MgO)n clusters as a function of size (n).
• To predict the electronic properties and reactive sites of these clusters.

Main Methods:

• Global minima optimization using a tree growth-hybrid genetic algorithm.
• Calculations performed with MNDO/MNDO/d semiempirical molecular orbital methods.
• Density functional theory (DFT) geometry optimizations using the B3LYP functional.

Main Results:

• New lowest energy isomers were identified for various (MgO)n clusters.
• For n > 3, 3-dimensional structures are most stable; hexagonal tubular structures are favored for n < 20.
• Cubic structures dominate for n > 20, with stability increasing with size and compactness.

Conclusions:

• The structural preferences of (MgO)n clusters transition from tubular to 3D/cubic with increasing size.
• Bond distances and coordination numbers approach bulk values as n increases.
• Electronic properties indicate reactive sites are primarily located at the corners of the clusters.