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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hi,

Could you please post your input file ?
Theoretically (and in practice (see test 24 in the v3 serie)) abinit
can perform your calculation in spgroup 227 without problem. Thus, it
could be quite helpful to see your input file in order to know what
the problem could be.

regards

PMA

On Wed, Oct 22, 2008 at 7:04 AM, Andrey Chibisov
<andreichibisov@yandex.ru> wrote:
> Can you help me with unit cell of Cristobalite?
> Data for Cristobalite from site http://rruff.geo.arizona.edu/AMS/amcsd.php 
> (American Mineralogist Crystal Structure Database) is:
>
> Title               Cristobalite
> Lattice type        F
> Space group name    Fd-3m
> Space group number  227
> Setting number      1
>
> Lattice parameters
>   a        b        c       alpha    beta     gamma
>  7.16600  7.16600  7.16600  90.0000  90.0000  90.0000
> Unit-cell volume = 367.985229
> Structure parameters
>                       x          y          z          g          B
>   1 Si  Si          0.12500    0.12500    0.12500    1.000    3.335
>   2 O   O           0.00000    0.00000    0.00000    1.000    7.146
>
> In the input abinit file I write:
> spgroup 227
> For the primitive vectors of the lattice form a FCC lattice:
>  rprim
>        0.0 0.5 0.5
>        0.5 0.0 0.5
>        0.5 0.5 0.0
> However the abinit gives out:
> Unit cell is not primitive?
> In what is my error?
>
> --
> Andrey Chibisov.
> Candidate of Science,
> Structural Ceramics Laboratory
> Institute of Geology and Nature Management
> Far Eastern Branch of Russian Academy of Sciences
>



-- 
Pierre-Matthieu Anglade