[Pw_forum] subtile error for non collinear calculations with a GGA pseudo

Cyrille Barreteau cyrille.barreteau at cea.fr
Mon Feb 21 13:59:50 CET 2011

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

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 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

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 Barreteau              | phone : +33 (0)1 69 08 29 51
CEA Saclay                     | fax   : +33 (0)1 69 08 84 46
IRAMIS  SPCSI Bat 462          | email cyrille.barreteau at cea.fr
91191 Gif sur Yvette FRANCE
home page: http://iramis.cea.fr/Pisp/cbarreteau/
Lab page:  http://iramis.cea.fr/spcsi/

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