I am able to calculate the Rashba parameter for primitive structures directly from the band structure using Quantum ESPRESSO. However, for supercells, such as a 22-layer Au(111) slab with a 2×2 unit cell, or for heterostructures, I cannot directly observe the band splitting due to the folding of the Brillouin zone. In such cases, it is necessary to unfold the band structure to analyze the splitting.

Is there any package or tool available that can perform the unfolding of the band structure and assist in calculating the Rashba parameter for systems like a 22-layer Au(111) slab or heterostructures?

Any guidance or suggestions would be greatly appreciated!