Augmented Plane Waves (both APW and LAPW), band structure computation
Band structure for Cu, using augmented plane waves, the main reference is Computational Physics by Jos Thijssen https://www.cambridge.org/core/books/computational-physics/BEE73B0139D4A9993193B57CDC62096E
Description is on Computational Physics Blog: https://compphys.go.ro/augmented-plane-waves/