[Pw_forum] error in Wyckoff positions

[Giovanni Cantele]

for crystal_sg units, at each atomic site, you have to specify only those coordinates that cannot be inferred from the Wyckoff letter. From Modules/wypos.f90 (under space_group=64) :
            ELSEIF (TRIM(wp)=='8f') THEN
               tau(1)=0.0_DP
               tau(2)=inp(1)
               tau(3)=inp(2)

so if you remove the “0” (1st coordinate) it should work. This is specified in Doc/INPUT_PW.txt:

 When atomic positions are of type crystal_sg coordinates can be given
                            in the following four forms (Wyckoff positions):
                               C  1a
                               C  8g   x
                               C  24m  x y
                               C  48n  x y z
                            The first form must be used when the Wyckoff letter determines uniquely
                            all three coordinates, forms 2,3,4 when the Wyckoff letter and 1,2,3
                            coordinates respectively are needed.

                            The forms:
                               C 8g  x  x  x
                               C 24m x  x  y
                            are not allowed, but
                               C x x x
                               C x x y
                               C x y z
                            are correct.



Giovanni


> On 26 Jun 2017, at 16:31, Magdalena Birowska <Magdalena.Birowska at fuw.edu.pl> wrote:
> 
> Dear QE users;
> 
> I am trying to define the positions of atoms by used of the Wyckoff positions.
> Part of my input file concerning the topic is as follows:
>   
>  ibrav = 0 ,
>  A = 1, 
> space_group = 64 ,
> CELL_PARAMETERS {alat} 
>      3.298193909       0.0000000000       0.0000000000
>      0.0000000000      10.119663752       0.0000000000
>      0.0000000000       0.0000000000      4.120911577
> ATOMIC_SPECIES
> P  30.97 P.pz-hgh.UPF
> ATOMIC_POSITIONS {crystal_sg}
>  P 8f 0.000000 0.101300 0.078900
> 
> According to the manual when atomic positions are of the type crystal_sg have the form "C 48n x y z ",
> therefore I do not really understand the error mesage:
>      Error in routine read_cards (2):
>      wrong number of columns in ATOMIC_POSITIONS
> 
> Could anybody help me?
>  Magda Birowska 
> -- 
> Magdalena Popielska (Birowska)
> 
> Faculty of Physics
> University of Warsaw
> 
> ul. Pasteura 5, PL-02-093 Warszawa room no. 5.02
> Phone: 22 55 32902 (Office)
> Email: Magdalena.Birowska at fuw.edu.pl <mailto:Magdalena.Birowska at fuw.edu.pl>
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-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.fisica.unina.it/~cantele

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