[Pw_forum] igk files

[Lorenzo Paulatto]

On 02/21/2014 09:45 AM, Caloma Trumica wrote:
> Dear all,
>
> What data are stored in *.igk{n} files? Also, which f90 code controls 
> the output of the igk files.
>

  \psi_k(r)  = exp(-i r.k) \sum_G u_G exp( -i G.r)
                   = \sum_G u_G exp( -i (G+k).r)

The G vectors are sorted on the FFT grid in a regular order, i.e. in 
unit of reciprocal lattice vectors
G_1 =  (0,0,0)
G_2=(0,0,1)
..
G_nx=(0,0,nx-1)
G_nx+1=(0,1,0)
...
G_nx*ny*nz=(nz-1,ny-1,nx-1)

Note that this set of point form a box with the same shape as the 
reciprocal lattice unit cell (but much larger).

However, the condition on the cutoff  selects a sphere of valid G 
points, such as |G+k|^2 < ecutwfc.

The file igk (one for each k point) contains the list of G vector such 
that |G+k|^2 < ecutwfc, sorted in order of increasing |G+k|


The list is generated by ./PW/src/gk_sort.f90 and written just afterward 
in hinit0.f90 (and in many otehr palces in other codes)

HTH

cheers

> Thanks a lot.
>


-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
+33 (0)1 44 275 084 / skype: paulatz
http://www-int.impmc.upmc.fr/~paulatto/
23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05


-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 2956 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20140221/a0f64c48/attachment.p7s>