Dear Evan,
On 31/10/2016 08:51, evan wrote:
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.
then I would suggest that you get familiar with the concepts of real and
reciprocal space, supercells and refolding of points in the Brillouin zone.
In your calculation 16 valence bands are computed. Did you wonder why
and what they are ?
The coordinates of the X point are not your problem.
regards,
stefano
---
On two occasions I have been asked [by members of Parliament!], "Pray, Mr.
Babbage, if you put into the machine wrong figures, will the right answers
come out?" I am not able rightly to apprehend the kind of confusion of
ideas that could provoke such a question.
-- Charles Babbage
Regards
Evan
USC, China
At 2016-10-31 14:32:53, "Stefano de Gironcoli" <[email protected]> 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 <[email protected]
<mailto:[email protected]>> 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" <[email protected]
<mailto:[email protected]>> 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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