This demonstrates the use of Slabify.bfield.
It makes two bandstructures starting from an unpolarized full
relativistic model.
The first with a global B=1.1eV on all orbitals and the second
with B=1.1eV at the 3d-orbitals and B=0.2eV at 4sp-orbitals.
Both are shifted in erergy while plotting to correct the Fermi
energy.
Note, that the calculation with a smaller field at 4sp is better
at the band bottom.