Tight-binding description of graphyne and its two-dimensional derivatives

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Graphynes and related two-dimensional carbon compounds (2DCCs) exhibit unique electronic properties.
• Understanding their band structures is key to unlocking potential applications.

Purpose of the Study:

• Investigate the band structures of alpha-graphyne and its derivatives.
• Develop and refine computational models for accurate band structure prediction.
• Identify mechanisms for tuning the electronic properties of these 2DCCs.

Main Methods:

• Employed tight-binding approximations, including "two-site" and "all-atom" models.
• Renormalized the "two-site" model to capture essential band-gap features.
• Derived and utilized an "all-atom" model incorporating all pz orbitals for improved accuracy.
• Performed density functional theory (DFT) calculations for comparison.

Main Results:

• The renormalized "two-site" model effectively describes band-gap features in alpha-graphyne and 2DCCs.
• Identified adatom addition and heteroatom substitution as methods for tuning graphyne band gaps.
• The "all-atom" model demonstrates superior performance in describing DFT band structures.
• Attributed flat bands in DFT calculations primarily to the pz orbitals of edge carbons.

Conclusions:

• The developed tight-binding models provide insights into the electronic properties of graphyne-based 2DCCs.
• The study offers strategies for designing novel graphyne and graphdiyne-based materials.
• Findings facilitate the exploration of new applications for these advanced carbon materials.