Band unfolding made simple

Area of Science:

• Condensed matter physics
• Materials science
• Computational materials science

Background:

• Supercell calculations are essential for studying defects and complex structures in materials.
• Analyzing the electronic band structure of these systems can be challenging due to periodicity.
• Existing band unfolding methods may lack simplicity or broad applicability.

Purpose of the Study:

• To present a simple and intuitive method for band unfolding of energy bands from supercell calculations.
• To provide a valid approach for both periodic and non-periodic systems.
• To implement the algorithm and demonstrate its utility on benchmark examples.

Main Methods:

• Relating the local density of states in reciprocal space to the fully unfolded band structure.
• Refolding the bands into the primitive Brillouin zone of the pristine crystal.
• Implementation within the Siesta computational package.

Main Results:

• The proposed method offers an intuitive approach to band unfolding.
• The technique is applicable to a wide range of systems, including those lacking translational symmetry.
• Successful application to benchmark examples, including crystal defects and rotated graphene bilayers under pressure.

Conclusions:

• The presented band unfolding method is simple, intuitive, and broadly applicable.
• It provides a valuable tool for analyzing electronic structures in complex materials.
• The implementation in Siesta facilitates its use in computational materials science research.