Band-structure calculation using meta-GGA functionals
Band-structure calculations for meta-GGA functionals require multiple steps. Below we give a step-by-step introduction and an example. Additionally, we provide some advice to reduce computational and human effort.
Step-by-step instructions
For meta-GGA functionals, the Hamiltonian cannot be expressed in terms of the electronic charge density alones, but requires also the kinetic-energy density. Instead, the Kohn-Sham orbitals on a regular k mesh are required for any calculation within the formalism of hybrid functionals. The regular k mesh must be supplied in the KPOINTS file. Consequently, restarting a hybrid calculation requires the WAVECAR file of the previous self-consistent-field (SCF) run. This is in contrast to density-functional theory (DFT), where the electronic charge density written to the CHGCAR file suffices to restart a DFT calculation. In order to reach convergence more quickly, it is good practice to first compute the DFT result in a SCF calculation.