Mapping the superconducting energy gap on the Fermi surface in BZ

General discussion around the EPW software

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YSW
Posts: 19
Joined: Fri Jun 18, 2021 5:24 am
Affiliation: Shanghai University of Electric Pow

Mapping the superconducting energy gap on the Fermi surface in BZ

Post by YSW »

Dear all,

I have a problem about fermi surface.
I see the tutorial vedio that explains how to use the scripts in conjunction with VESTA.But it is a fermi surface in real space.
How can I get fermi surface in BZ?

A superconducting energy gap fermi surface in BZ of LaBH8.
Roxana shows it in the youtube video: Superconductors and Eliashberg theory - Roxana Margine.(55:23)
but she have not teach me how to get it.

I need you help badly.

Regards

hlee
Posts: 294
Joined: Thu Aug 03, 2017 12:24 pm
Affiliation: The University of Texas at Austin

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by hlee »

Dear YSW:
But it is a fermi surface in real space.
I don't think so; very naturally, according to the definition of Fermi surface it is in reciprocal space.

Sincerely,

H. Lee

YSW
Posts: 19
Joined: Fri Jun 18, 2021 5:24 am
Affiliation: Shanghai University of Electric Pow

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by YSW »

Dear H. Lee:

Yes,you are right.But,if I want to limit the image in 1st BZ.
What I need to do ?

Just like this
Image


Sincerely,

YSW

YSW
Posts: 19
Joined: Fri Jun 18, 2021 5:24 am
Affiliation: Shanghai University of Electric Pow

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by YSW »

Dear H. Lee:

This image is invisible likely.
So,I provide the link of this image.

https://www.researchgate.net/publicatio ... -right.jpg


Sincerely,

YSW

hlee
Posts: 294
Joined: Thu Aug 03, 2017 12:24 pm
Affiliation: The University of Texas at Austin

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by hlee »

Dear YSW:

It seems that you want to plot the Fermi surface in the first Brillouin zone instead of primitive Brillouin zone.
With Vesta you can't do it and you need to use other programs with the suitable file format.

One of programs I know is the Fermisurfer (https://fermisurfer.osdn.jp/), but you need to convert the output generated by EPW into the format Fermisurfer can support.

It is not difficult and please check the chapter 4 of its manual at https://fermisurfer.osdn.jp/en/_build/l ... surfer.pdf .

Sincerely,

H. Lee

YSW
Posts: 19
Joined: Fri Jun 18, 2021 5:24 am
Affiliation: Shanghai University of Electric Pow

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by YSW »

Dear H. Lee:

Thank you very much for your help and advice.

Code: Select all

real(4) :: bvec1(3), bvec2(3), bvec3(3) ! Resiplocal lattice vector
integer :: nk1, nk2, nk3 ! k-grid of each direction
integer :: ishift ! 1 for shifted grid, 0 for unshifted grid.
integer :: nbnd ! The number of bands
real(4) :: eig(nk3,nk2,nk1,nbnd) ! energy
real(4) :: x(nk3,nk2,nk1,nbnd) ! matrix element
integer :: ik1, ik2, ik3, ibnd, fo
open(fo, file = "sample.fs")
write(fo,*) nk1, nk2, nk3
write(fo,*) ishift
write(fo,*) nbnd
write(fo,*) real(bvec1(1:3))
write(fo,*) real(bvec2(1:3))
write(fo,*) real(bvec3(1:3))
do ibnd = 1, nbnd
do ik1 = 1, nk1
do ik2 = 1, nk2
do ik3 = 1, nk3
write(fo,*) real(eig(ik3,ik2,ik1,ibnd))
end do
end do
end do
end do
do ibnd = 1, nbnd
do ik1 = 1, nk1
do ik2 = 1, nk2
do ik3 = 1, nk3
write(fo,*) real(x(ik3,ik2,ik1,ibnd))
end do
end do
end do
end do
close(fo)
In this code,how shouid I set the matrix element ? Which output generated by EPW is included it ?

If I want to plot the superconducting energy gap fermi surface.
I use Prefix.imag_aniso_gap_FS_010.00, and the energy part is set delta(0) [meV],is it right?

Thank you again.

Sincerely,

YSW

hlee
Posts: 294
Joined: Thu Aug 03, 2017 12:24 pm
Affiliation: The University of Texas at Austin

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by hlee »

Dear YSW:

delta(0) should go to the part of "real(x(ik3,ik2,ik1,ibnd))" and band energies should go to the part of real(eig(ik3,ik2,ik1,ibnd)) .

Sincerely,

H. Lee

YSW
Posts: 19
Joined: Fri Jun 18, 2021 5:24 am
Affiliation: Shanghai University of Electric Pow

Re: Mapping the superconducting energy gap on the Fermi surface in BZ

Post by YSW »

Dear H. Lee:

Thank you for your guidance.
But,I have to say,I am a green hand.and I have some problems about using this script.

How should I execute this script ?
Need I use Prefix.imag_aniso_gap_FS_010.00 and nscf.out ? If I need, How should I use the date with this script ?


Sincerely,

YSW

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