Ti₁₂C₆₈: A stable T _h -symmetry hollow cage

Area of Science:

• Computational Chemistry
• Materials Science
• Inorganic Chemistry

Background:

• Hollow metal carbide clusters are of interest for their unique structural and electronic properties.
• Investigating novel cluster structures is crucial for expanding the library of known materials.

Purpose of the Study:

• To systematically investigate the structural, kinetic, and electronic properties of a stable Th-symmetry Ti12C68 cage.
• To assess the thermal stability and bonding characteristics of this novel titanium carbide cluster.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to determine the electronic structure and stability.
• Ab initio molecular dynamics simulations were used to evaluate thermal stability up to 1139 K.
• Natural Bond Orbital (NBO) and frontier molecular orbital analyses were performed to understand bonding and electronic properties.

Main Results:

• The Ti12C68 cluster possesses a stable hollow cage structure with Th symmetry, confirmed by the absence of imaginary frequencies.
• Molecular dynamics simulations showed the structural integrity of the cage was maintained up to 1139 K.
• Analysis revealed significant Ti d-orbitals contribution to four sigma bonds within each TiC13 subunit, crucial for cluster stability.
• A narrow HOMO-LUMO gap was observed, indicating metal-like electronic properties.

Conclusions:

• The Ti12C68 cage is kinetically stable and exhibits high thermal stability.
• The electronic structure suggests potential for unique applications due to its metal-like properties.
• This finding enriches the family of hollow metal carbide clusters and opens avenues for further research.