[QE-users] how to select the perturbed atoms in phonon single q calculation ?

[Tamas Karpati]

did you try nogg=.true. ?
if not, i suggest you to apply the minimum necessary amount of
parameters in your input file.

On Wed, Oct 28, 2020 at 3:14 PM Omer Mutasim <omermutasim at ymail.com> wrote:
>
> I just tried but i got the following error message:
>
> "
>      Error in routine phq_readin (1):
>      gamma_gamma tricks with nat_todo  not available. Use nogg=.true.
>
> "
> i'm doing single q phonon calculation
> any help ?
> On Wednesday, October 28, 2020, 05:45:15 PM GMT+4, Tamas Karpati <tkarpati at gmail.com> wrote:
>
>
> Dear Omer,
>
> Did you try to use the nat_todo option in your PH.x input file?
> (Do not forget to list the perturbed atom indices on the last line.)
>
> ASE can use QE as "calculator" and I think it can do what you want.
> If not, use Phonopy.
>
> HTH,
>   t
>
> On Wed, Oct 28, 2020 at 1:28 PM Omer Mutasim <omermutasim at ymail.com> wrote:
> >
> >
> > Dear all
> >
> >  I need to calculate the the virbrational frequencies of adsorbate molecule on surface using phonon single q calculation  , in order to estimate the partition function (for entropy ,reaction rate constants). so my questions go like:
> >
> >  I have a large supercell (110 atoms) which means a high degrees of freedom (330 DOF) ,  so i want to decrease this DOF , by perturbing only adsorbate molecule and the the two uppermost layers
> >
> > how to select the perturbed atoms in quantum espresso ?
> > I have heard that it can be done by finite difference method, which wasn't employed in QE.
> > However, i have seen a post where Dr. Paolo Giannozzi said: " it can be performed by two finite-difference calculations with opposite displacements "
> > So , can you please tell me, what are the steps involved in doing this finite-difference method mentioned by Dr. Paolo ? or any other procedure that can be do the same ?
> >
> >
> >  Thanks in advance
> >
> >
> >
> >
> > Omer Elmutasim
> > Research Assistant
> > Chemical Engineering Department
> > Khalifa university- UAE
>
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