[Pw_forum] Doubt in band plot

[xirainbow]

Dear Padmaja Patnaik:

 I am plotting band structure for cubic SiC. Got good shape when compared.
> SiC has an indirect band gap. Next I tried to plot the band structure of
> cubic SIC with a supercell. I have expanded the lattice constant by twice in
> all direction and generated supercell with Phonon code. Now the band plot of
> this supercell shows direct band gap. how is this possible? It is expected
> that even if the supercell should produce the same band plot.

When you expand the lattice constant, the Brillouin Zone will be folded.
Therefore, the indirect gap may turn into direct gap.
If you plot the dos, the primitive cell and supercell will give the same
shape, but the bands are different.

Please suggets.
>
> Thanking in advance
> regards
> Padmaja Patnaik
> Research Scholar
> Dept of Physics
> IIT Bombay
> Mumbai, India
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>


-- 
____________________________________
Hui Wang
School of physics, Fudan University, Shanghai, China
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