[Pw_forum] The coordinate of X-point in GaAs band structure calculation

[evan]

Dear Stefano

Thank you for your reply, but I do not understand what’s you meaning in the last letter.

What I want to know is that when the lattice structure of GaAs (fcc) is different from the simulation cell (sc, ibrav =1 in my calculations), the coordinates of high symmetry points in Brillioun zone of which lattice structure (fcc or those of sc) I should specify in the PWscf input file?

I am not familiar with this issue, but it is important for my study. Thank you for your patience.

Regards

Evan

USC, China






At 2016-10-31 14:32:53, "Stefano de Gironcoli" <degironc at sissa.it> wrote:

The one you are using: ibrav=1.
Do not expect to see a band structure similar to the usual one tho

stefano 
(sent from my phone)

On 31 Oct 2016, at 03:03, evan <ewan26 at 126.com> wrote:



Dear Stefano and Andrew

Thank you for your kind replies. Let me ask a more general question which I think about.

 I want to calculate the band structure of GaAs (FCC structure) in a simple cubic lattice cell with eight atoms (ibrav =1). If I specify the k points in units of 2pi/a (K_POINTS tpiba_b), the high symmetry points in Brillioun zone of which cell I should specify in the input file, FCC (ibrav =2) or those of SC (ibrav=1) lattice structure?

If I specify the k points in in crystal coordinates(K_POINTS crystal_b), then of which cell I should specify the k points in the input files, FCC or SC lattice structure.

Thank you in advance.

Regards

Evan

USC, China


At 2016-10-30 02:17:33, "stefano de gironcoli" <degironc at sissa.it> wrote:

Dear Evan,
   GaAS structure is zincblend (2 atoms per cell). its X point is indeed 2pi/a(1,0,0).
   if you choose to compute GaAs in a SC cell (8 atoms pr cell) then that point is indeed equivalent to Gamma. The zone boundary of the SC cell is pi/a(1,0,0) but this of course does not correspond to the X point of the zincblend structure.
  HTH
 stefano

On 29/10/2016 16:00, evan wrote:


Hello, everyone

I calculated the band structure of GaAs in a simple cubic lattice cell (ibrav=1), I searched from the internet the coordinates of X-point in the first Brillouin zone are 2pi/a(0,0,1) or 2pi/a(1,0,0), but both results show that band gap occurs at G and X points simultaneously, it seems to me that the X is equivalent to G, can you tell me the correct X point coordinates which give me the reasonable result. The input files and results are attached, you can show what is wrong in the input file.

Your suggestions are appreciated.

Yours sincerely

Evan

USC, China 





 





 




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