[QE-users] Wrong phonon dispersion (Au) along X-K direction

[Lorenzo Paulatto]

Hello,

it looks to me like your phonons are correct, but the matdyn path may 
not be.

The X->W->X line is actually quite tricky, because you are going from a 
X point on the border of the 1st Brillouin zone to an equivalent X 
(let's call it X²) point on the border of the 2nd zone, afterward, the 
X²→K path is also different. I don't think that the syntax you used for 
matdyn can capture this.

The coordinates of the "X" and "X²" point in units of 2pi/alat are:

1.0000000000    0.0000000000    0.0000000000 X
1.0000000000    1.0000000000    0.0000000000 X²

Then, the line that from X² goes back to Gamma passes through one of the 
K points on the border of the 1st BZ, which has coordinates

0.7500000000    0.7500000000    0.0000000000 K

(again in units of 2pi/alat) The path is simply:

0.0000000000    0.0000000000    0.0000000000 Γ
1.0000000000    0.0000000000    0.0000000000 X
-- k is somewhere here --
1.0000000000    1.0000000000    0.0000000000 X
0.0000000000    0.0000000000    0.0000000000 Γ
0.5000000000    0.5000000000    0.5000000000 L


hth

p.s. I.e. as Stefano said.

On 30/10/2024 19:34, Md. Jahid Hasan Sagor wrote:
> Hi,
>
> I calculated phonon dispersion and compared it with other studies. 
> However, dispersion is matched with every k direction except X-K. 
> Would you please tell me how to solve the issue? Should I use a 
> different pseudopotential? I am sharing here the 
> dorg/mailman/listinfo/users
-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université
phone: +33 (0)1 442 79822 / skype: paulatz
http://www.impmc.upmc.fr/~paulatto/ - https://anharmonic.github.io/
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