[Pw_forum] phonon calculation for optimized geometry -one subtle confusion

Paolo Giannozzi giannozz at democritos.it
Sun Apr 18 19:29:09 CEST 2010

On Apr 18, 2010, at 13:30 , mohnish pandey wrote:

> when I am doing scf calculation with the geometrical parameters
> value obtained from the vc-relax calculation the pressure value is
> different from vc-relax final run.

as explained a diverging number of times (even recently): the
plane-wave basis set used during variable-cell calculations is
determined by the given cutoff and the INITIAL cell. If you
make a calculation with the final geometry at the same cutoff,
you may get slightly different  results. The difference should
be small, though.

Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222

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