[Pw_forum] Phonon calculation

[Paolo Giannozzi]

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