[Wien] Vacancy problem with Wien2k

[Daniel Kmiec]

Dear Wien2k users,

I am quit new user of Wien2k, I tried to find answer for my question
in usersguide an mailing list but without luck.
Since some time I'm trying to calcute a surface system with a vacancy.

(for good display please use fixed font width)
This shows, how one layer looks like?
It is bcc 110 surface
O - vacancy
* - atom

top view of the surface

O ----------- * ----------- * ----------- O
|             |             |             |
|      *      |      *      |      *      |
|             |             |             |
* ----------- * ----------- * ----------- *
|             |             |             |
|      *      |      *      |      *      |
|             |             |             |
* ----------- * ----------- * ----------- *
|             |             |             |
|      *      |      *      |      *      |
|             |             |             |
O ----------- * ----------- * ----------- O

I have 5 such layers defined

vacum
surface   .................
substrate -----------------
substrate -----------------
substrate -----------------
surface   .................
vacum

The vacancy is only on surface, the substrate contains all atoms.

Now comes my question, when I'm not wrong in this case I should have 18
atoms per layer(or 17 + vacancy on the surface). This gives the total
number of atoms 88 + 2 vacancies. The symetry group I have in this case
is Pmmm and I have 23 inequivalent atoms.
Maybe this is a silly question but in "case.outputs" file I found line 
which says that the number of atom is 352 (also 4 times bigger).

After the list of all 88 atoms with positions comes section:

DETERMINATION OF POINTGROUP FOR ALL POSITIONS
and there i see lines like this
...
Fe        :  16 Atoms, Index  337 to  352
number of atoms: 352
...

I would like to know what is Wien2k doing here? It tries to generate all 
possible positions of atoms, and then reduce the total number to only 
inequivalent ones ? I hope it is calculating _only_ the cell with 88 atoms.

Best regards
Daniel Kmiec

-- 
____________________________________________________
Daniel Kmiec
Institut für Materialphysik
Strudlhofgasse 4	      Tel : +43 1 4277 51310
1090 Wien, Austria	      Fax : +43 1 4277 9513