Problem with Plotting Fermi Surfaces

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shima123
Posts: 5
Joined: Tue Jun 11, 2019 12:25 pm

Problem with Plotting Fermi Surfaces

Post by shima123 » Thu Nov 07, 2019 6:04 pm

Hi,
I am calculating band structure and fermi surfaces for a narrow-gap semiconductor using LDA, full relativistic, NC PPs.
When I plot band structure I see a band gap of about 0.04eV, but When I want to plot Fermi Surfaces using Xcrysden by .bxsf file, I saw some overlap between Valance and Conduction band, i.e. there is some contribution from valance bands at Fermi level.

Could you please guide me what is the problem with that?

I followed the instructions written for "prtfsurf" (iscf2:-3 ,prtfsurf2 1, defined suitable nbnd and a really dense kpoint grid with zero shift) for plotting Fermi surfaces and used my optimized parameters and atomic positions:
iscf2 -3
getden2 -1
kptopt2 1
nshiftk2 1
shiftk2 0.0 0.0 0.0
ngkpt2 50 50 50
nband2 40
tolwfr2 1.0d-18
enunit2 1
prtfsurf2 1

Then, my next question is that I want to run my calculations for fermi surfaces using "Tetrahedra Method". I'd appreciate if you could guide me how to do that.

Thank you so much!

Best,
Shima

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