[QE-developers] "Error in routine set_irr_sym_new"

[Merlin Meheut]

Dear Lorenzo, Paolo,

I have successfully sent PHonon code after uncomenting the line you
suggested, thank you very much for your help (it will take some time to get
the final result, though, but I am confident that it will work). And for
your answer below, as well. The garnet structure is quite unique as it is
at the same time very big and very symmetric. So I guess this type of
configurations has little chance to happen in other circumstances. I guess
I will compute this structure "the old way" and re-comment the line
afterwards, to prevent pathological cases.

Thanks again,

Merlin

Le jeu. 7 mai 2020 à 10:14, Lorenzo Paulatto <paulatz at gmail.com> a écrit :

> I forgot to answer to the list before.
> I confirme that using the "old" random matrix it "works" in the sense
> that this specific case works. It will fail in other cases though.
>
> cheers
>
> On 5/7/20 9:31 AM, Lorenzo Paulatto wrote:
> > Yes,
> > the phonon code checks if modes are degenerate by symmetrizing a random
> > matrix and checking if the eigenvalues are the same. For a sufficiently
> > large systems there are going to be accidental degeneracies.
> >
> > Can you try to uncomment
> > !!#define __UNIFORM_DISTRIB
> > in PHonon/PH/random_matrix.f90 and see if it fixes, or at least changes,
> > the error?
> >
> > cheers
> >
> >
> >
> >
> > On 5/7/20 9:25 AM, Paolo Giannozzi wrote:
> >> This phonon error shows up quite frequently, especially in large cells:
> >>
> https://www.mail-archive.com/search?a=1&l=users%40lists.quantum-espresso.org&haswords=set_irr_sym_new&x=14&y=14&from=&subject=&datewithin=1d&date=&notwords=&o=newest
> >>
> >> While in most cases it is due to "quasi-symmetric" atomic positions
> >> and cells, in this case:
> >>
> https://www.mail-archive.com/users@lists.quantum-espresso.org/msg37662.html
> >>
> >> the reasons is no so obvious. Any idea?
> >>
> >> Paolo
> >> --
> >> 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
> >>
> >>
> >> _______________________________________________
> >> developers mailing list
> >> developers at lists.quantum-espresso.org
> >> https://lists.quantum-espresso.org/mailman/listinfo/developers
> >>
> >
>
> --
> Lorenzo Paulatto - Paris
>


-- 
Merlin Méheut
adresse labo:
GET - OMP   - Université Paul Sabatier
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