[Pw_forum] Phonon calculation
Paolo Giannozzi
paolo.giannozzi at uniud.it
Mon Oct 7 10:43:40 CEST 2013
On Mon, 2013-10-07 at 09:48 +0300, Uri Argaman wrote:
> It's worth to set nimage equal to the number of q-points
> in the phonon calculation?
not necessarily so. Different wave-vectors may have different
workloads: not by order of magnitudes, but a low-symmetry
wave-vector may easily take 5 times more CPU than a high-symmetry
one.
> In addition I want to ask how the complexity of the phonon calculation
> depends on the number of the k-points (in the PW calculation)
roughly linearly, but the number of actual k-points in phonon
calculations depends upon the symmetry and the wave-vector
> and how the number of k-points affects the accuracy of the phonon
> calculation.
more or less (more rather than less) in the same way as it affects
the calculation of other structural properties; quantities related
to the electric field (effective charges and dielectric tensors)
tend to converge more slowly with the number of k-points
P.
--
Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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