Re: [Phonopy-users] Harmonic force constants calculation with QE interface

[Seyed V. H. <vah...@gm...>]

Hello Dear Armin

For the question 1:
In the Force-set file, the displacements and forces on each atom is written
in this file which are calculated by quantum espresso.
If you want to observe the force constants elements you should put
WRITEDM = .TRUE.
FORCE_CONSTANTS = WRITE
in your band.conf file.
After running the command, the force constants are written into
FORCE_CONSTANTS txt file.

Good luck
Vahid

On Thu, Jan 16, 2020 at 7:57 PM Armin Taheri <arm...@gm...> wrote:

> Hello,
>
> I am a new user of phonopy. I am trying to find the force constant matrix
> for a system using phonopy and my interface is quantum espresso. I will
> then use that force constant matrix for other packages such as ShengBTE
> or Hiphive. I have 2 questions about phonon calculations and harmonic force
> constants:
>
> 1- Based on the instruction explained here
> <https://atztogo.github.io/phonopy/qe.html> for NaCl, I think I can only
> get "FORCE_SETS" using QE as the interface. I was wondering what is the
> difference between  FORCE_SETS  and FORCE_CONSTANTS, and how can I obtain FORCE_CONSTANTS
> using phonopy and QE interface.
>
> 2- What is the difference between " --pwscf " tag and "--qe"  tag when
> dealing with phonon calculation with quantum espresso interface. I noticed
> that in the phonopy examples, --pwscf is used for Si while --qe is used for
> NaCl.
>
>
>
> Thanks,
>
> Armin
>
>
>
>
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