[Q-e-developers] Reporting bug in QE ph.x

[Paolo Giannozzi]

Thank you Giuliana. While waiting for better solutions, the best way
to communicate problems and proposed solutions is via the
q-e-developers mailing list (CC:).

It is likely sufficient to modify the function reset_grid as follows:

       reset_grid = (nk1_*nk2_*nk3_ > 0)
       IF ( .NOT. reset_grid ) RETURN
       nk1 = nk1_
       nk2 = nk2_
       nk3 = nk3_
       k1 = k1_
       k2 = k2_
       k3 = k3_

but given the complexity of linear-response codes I cannot rule out
unexpected side effects

Paolo


On Fri, Apr 7, 2017 at 7:38 PM, Giuliana Barbarino
<giuliana.barbarino at polytechnique.edu> wrote:
> Dear Paolo Giannozzi,
> I am Giuliana Barbarino and I am a Postdoc at the Laboratoire des Solides
> Irradies in Ecole Polytechnique. My supervisor is Nathalie Vast and I work
> with Jelena Sjakste on a project about electron-phonon coupling.  Nathalie
> suggested me to write to you because I found a problem on PH code. It
> regards the possibility to reset a new grid of k-points inside Phonon.
>
> If the self consistent calculation is performed with an automatically
> generated Monkhorst-Pack grid (nk1,nk2,nk3) and with the grid offset
> k1=1,k2=1,k3=1 and in the phonon input it is specified a new k-points grid
> to run the pw non-self consistent calculation without offset
> k1=0,k2=0,k3=0, the phonon code doesn't change the grid and it performs
> anyway the calculation with (nk1,nk2,nk3,1,1,1).
> This also if any k1,k2,k3 is specified by input, even if the default
> values of k1,k2,k3 variables should be 0.
>
> The reset_grid function, called in phq_readin and defined in the
> subroutine  start_k of PW code, resets the automatic grid to new values
> only if these are > 0. The (nk1,nk2,nk3,k1,k2,k2) defined in start_k are
> then used to setup the non-self consistent calculation.
>
> This bug is not important in the case of a simple phonon calculations but
> it affects my results in the case of electron-phonon calculation by using
> Wannier functions.
>
> I would like to ask you a suggestion about how I should proceed to
> communicate the corrections I have done to fix it.
>
> thank you for your help,
> Best regards
>
>
>
>
> Giuliana Barbarino
> Laboratoire des Solides Irradies
> Ecole Polytechnique
> Route de Saclay
> 91128 Palaiseau
> Phone: +33 1 69 33 45 15
>



-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222