[Wannier] Energy mismatch among symmetry equivalent states in silicon

[Vahid Askarpour]

Dear Wannier Users,

I have calculated the interpolated band structure of silicon (8 wannier functions) using a k grid of 8x8x8. I considered two segments:

1. From 0.05 0.4 -0.4 to 0.05 0.4 -0.5
2. From 0.85 0.4 0.3 to 0.85 0.4 0.4

My purpose in choosing these two segments is to compare the electronic energies at two symmetry equivalent points: (0.05,0.4,-0.45) and (0.85,0.4,0.35).

Here are the eight band energies (in eV) for the two points:

-2.2651301     -2.262256
-0.7977982    -0.7918293
2.5481431      2.5474092
3.3210793      3.4353798
7.3564264      7.340448
8.7099476      8.6832805
14.055428      14.064489
14.828398      14.849574

In case of diamond, these energies are identical. But for silicon, for example, band 4 is different by 100meV! Has anyone encountered this energy mismatch
and is there a way to deal with it?

Thank you,

Vahid


Vahid Askarpour
Department of Physics and Atmospheric Science
Dalhousie University,
Halifax, NS, Canada