K₄ Carbon Modifications by Modulating Phonon Eigenvectors

Area of Science:

• Materials Science
• Solid-State Physics
• Computational Chemistry

Background:

• The discovery of novel carbon allotropes is ongoing, with unique network topologies.
• The chiral K4 carbon structure, similar to diamond, was proposed but found dynamically unstable.
• This instability led to the disregard of K4 as a potential carbon structure.

Purpose of the Study:

• To stabilize the dynamically unstable chiral K4 carbon graph.
• To explore novel carbon allotropes derived from the K4 structure.
• To investigate the properties of these newly stabilized allotropes.

Main Methods:

• First principles calculations were employed to analyze and stabilize the K4 structure.
• Phonon eigenvectors associated with imaginary frequencies were modulated to address instability.
• Electronic structure and elastic properties were computed for the novel allotropes.

Main Results:

• Six novel, dynamically stable carbon allotropes derived from the chiral K4 graph were successfully generated.
• These allotropes exhibit chirality, lower symmetry than K4, and enhanced thermodynamic stability.
• The predicted materials are semiconductors with band gaps from 0.72 to 5.14 eV and are mechanically stable.

Conclusions:

• The stabilization of the chiral K4 graph yields new, stable carbon allotropes with promising semiconductor properties.
• Thermodynamic stability correlates inversely with the ratio of 3:4 connected carbon atoms.
• These findings open avenues for exploring new carbon-based materials with tailored electronic and mechanical characteristics.