[Pw_forum] RE : subtile error for non collinear calculations witha GGA pseudo

[BARRETEAU Cyrille]

Andrea,
 
Thanks for your anwer. I will therefore download the CVS version and do some testing.
 
By the way I have also noticed that some pseudopotentials generated by old version of ld1.x (typically older than 4.0.5) are no longer accepted by  pw. Does it mean that some errors were found in ld1.x. Or is it due to a modification of the format?
 
thanks
  cyrille
 
================================================================== 
Cyrille Barreteau                                                      phone : +33 (0)1 69 08 29 51 
CEA Saclay                                                             fax :      +33 (0)1 69 08 84 46 
IRAMIS, SPCSI,    Batiment 462                            email     cyrille.barreteau at cea.fr 
91191 Gif sur Yvette Cedex 
FRANCE 
~~~~~~~~~~~~~~~~~~~~~~~~ 
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________________________________

De: pw_forum-bounces at pwscf.org de la part de Andrea Dal Corso
Date: lun. 21/02/2011 18:39
À: PWSCF Forum
Objet : Re: [Pw_forum] subtile error for non collinear calculations witha GGA pseudo




On Mon, 2011-02-21 at 13:59 +0100, Cyrille Barreteau wrote:
> Dear all
>
> I have noticed an usual behavior when doing non collinear calculation
> with a GGA pseudopotential.
>
> During the iteration process there are some NaN appearing in the output
> file (see below). The strange thing is that the code continues and
> converges..
>
> iteration #  1     ecut=    35.00 Ry     beta=0.30
>      Davidson diagonalization with overlap
>      ethr =  1.00E-02,  avg # of iterations =  2.0
>               NaN         NaN         NaN

This error has been already corrected in the cvs version a few months
ago. Note however that GGA + noncollinear is less stable than the
other parts of QE.

HTH,

Andrea

>
> This type of Pb is not present when using a LDA pseudo.
>
> Moreover I have tried to do a calculation of a collinear configuration
> with or without the 'noncolin' option. In principle both should lead to
> almost the same solution. This is not the case. There are some
> differences which according to me are larger than just numerical
> errors..
>
> I guess there is some kind of Pb when performing non collinear
> calculations with a GGA pseudo.
>
> thanks to give me a hint to solve this problem
>
>   cyrille
>
--
Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Bonomea 265              Fax. 0039-040-3787249
I-34136 Trieste (Italy)             e-mail: dalcorso at sissa.it


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