Paolo Giannozzi giannozz at nest.sns.it
Mon Mar 7 23:06:59 CET 2005

On Monday 07 March 2005 18:59, Alcantara Ortigoza, Marisol wrote:

> I've been trying to calculate phonon frequencies in Cu100 at M point
> (using 18 atoms). I first did the self-consistent calculation using the
> relaxed postions of the surface, then a non-self consistent calculation
> using calculation = 'phonon' and specifying the q-vector in &PHONONS, 
> at this point I got extremely high or even undefined ( ***** ) forces,

forces in this case are meaningless and should not be calculated.

>      from davcio : error #        20
>      i/o error in davcio

Look carefully at the examples (3, 5, 6, 7) of phonon calculations.
Remove everything in the scratch directory and start from the beginning. 
Check that both the scf and the non-scf calculations have actually written
their files to the scratch directory.

Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy

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