In pursuit of accurate interlayer potentials for twisted bilayer graphynes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• The field of twistronics, inspired by twisted bilayer graphene, studies phenomena in layered materials with controlled interlayer twist.
• First-principles calculations for twisted layered materials are computationally expensive, hindering theoretical research.
• Empirical force fields with anisotropic terms offer a computationally efficient alternative for modeling interlayer interactions.

Purpose of the Study:

• To develop atomistic empirical potentials for capturing interlayer interactions in bilayer graphynes.
• To explicitly incorporate anisotropic effects in modeling the stacking, sliding, and twisting of bilayer graphynes.
• To provide a computationally feasible approach for theoretical studies in twistronics involving graphynes.

Main Methods:

• Calibration of empirical potentials, including the improved Lennard-Jones and Hod's interlayer potential, against dispersion-corrected Density Functional Theory (DFT) calculations.
• Incorporation of stacking, sliding, and twisting degrees of freedom in the DFT calculations for parameterization.
• Evaluation of the accuracy of isotropic and anisotropic potentials in describing interlayer energy profiles.

Main Results:

• The isotropic improved Lennard-Jones potential accurately describes interlayer stacking but fails to capture interlayer twist properties in bilayer graphynes.
• The anisotropic Hod's interlayer potential demonstrates reasonable accuracy in reproducing the interlayer twisting energy profiles from DFT benchmarks.
• Developed empirical potentials provide a viable alternative to computationally intensive first-principles methods for studying bilayer graphynes.

Conclusions:

• Anisotropic empirical potentials, specifically Hod's interlayer potential, are crucial for accurately modeling the twist-dependent behavior of bilayer graphynes.
• The developed potential formulations can significantly accelerate research on homo- and hetero-bilayer graphynes and other two-dimensional materials within the twistronics framework.
• This work facilitates the exploration of novel electronic and physical properties arising from interlayer coupling in van der Waals heterostructures.