[Pw_forum] A question about symmetry

Stefano de Gironcoli degironc at sissa.it
Mon Oct 1 17:48:54 CEST 2012

what the symmetrization does is not an average.
it is the projection on the totally symmetric group representation for 
tensorr of the given rank.
It is used to reconstruct the contribution from the symmetry equivalent 
kpoints that are eliminated when the symmetry is identified.


On 10/01/2012 04:56 AM, Caloma Trumica wrote:
> Dear all,
> I have a general question about the symmetry in the Quantum espresso
> program.
> For quantities such as the Hellmann-Feynman forces and the stress tensor,
> why do we need to divide they by the total number of symmetry operations.
> Dose it mean that any quantity reported in an electronic structure code is
> an average value?
> Thank you.
> Andy Lau
> Hong Kong
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