[QE-developers] "Error in routine set_irr_sym_new"

[Lorenzo Paulatto]

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
>>
>>
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>>
> 

-- 
Lorenzo Paulatto - Paris