[Pw_forum] RE : subtile error for non collinear calculations with aGGA pseudo

[BARRETEAU Cyrille]

Paolo,
 
In fact I have compared collinear and non collinear calculation for a "collinear situation" (bcc Cr AF): both calculations perfectly agree (up to numerical precision) for a LDA pseudo but not for a GGA pseudo. This is probaly due to the error mentionned previously (corrected in the CVS version). Therefore following Andrea's suggestion I will try the last cvs version to check that  gga pseudo work also..
 
good evening
 
  cyrille
 
 
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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 
~~~~~~~~~~~~~~~~~~~~~~~~ 
Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/ 
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________________________________

De: pw_forum-bounces at pwscf.org de la part de Paolo Giannozzi
Date: lun. 21/02/2011 20:55
À: PWSCF Forum
Objet : Re: [Pw_forum] subtile error for non collinear calculations with aGGA pseudo




On Feb 21, 2011, at 13:59 , Cyrille Barreteau wrote:

> 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.

in practise, they don't. It is a known problem (Andrea
explained it to me some time ago), not related to bad
coding but to a more fundamental and subtle problem
of how to define the quantization axis

P.
---
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222




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