[QE-users] Wyckoff site 8f missing from group 15

[Giovani Rech]

Hello all,

I’ve been trying to construct a crystalline structure of symmetry C2/c, unique axis b, space group 15. The atoms lie in the 8f Wyckoff positions (http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-wp-list?gnum=15&gua=b). I tried using 

> Space_group = 15
> Uniqueb = .true. 

And assigning the atoms sites as instructed by the manual

> ATOMIC_POSITIONS crystal_sg
> F 8f  0.285000000    0.31700000    0.099700000

However, the programs fails and can’t find the Wyckoff site to generate the entire structure for this symmetry. In fact, when inspecting the wypos.f90 module (around line 1048) I noticed that this site specifically was not implemented, so if anyone else is facing the same problem, this might be cause. 

I believe that the problem could be corrected by adding

> ELSEIF (TRIM(wp)=='8f') THEN
>        tau(1)=inp(1)
>        tau(2)=inp(2)
>        tau(3)=inp(3)

In the wypos_15 subroutine (but I’m not sure, correct me if I’m wrong). For the time being, I circumvented the problem by using ibrav=-12 and explicitly assigning each atomic position.

Best regards,

Giovani Rech
Universidade de Caxias do Sul
Caxias do Sul - RS, Brasil 
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